In
mathematics, a polynomial is an
expression
Expression may refer to:
Linguistics
* Expression (linguistics), a word, phrase, or sentence
* Fixed expression, a form of words with a specific meaning
* Idiom, a type of fixed expression
* Metaphorical expression, a particular word, phrase, o ...
consisting of
indeterminates (also called
variables) and
coefficients, that involves only the operations of
addition
Addition (usually signified by the plus symbol ) is one of the four basic operations of arithmetic, the other three being subtraction, multiplication and division. The addition of two whole numbers results in the total amount or '' sum'' of ...
,
subtraction
Subtraction is an arithmetic operation that represents the operation of removing objects from a collection. Subtraction is signified by the minus sign, . For example, in the adjacent picture, there are peaches—meaning 5 peaches with 2 taken ...
,
multiplication
Multiplication (often denoted by the cross symbol , by the midline dot operator , by juxtaposition, or, on computers, by an asterisk ) is one of the four elementary mathematical operations of arithmetic, with the other ones being addi ...
, and positiveinteger powers of variables. An example of a polynomial of a single indeterminate is . An example with three indeterminates is .
Polynomials appear in many areas of mathematics and science. For example, they are used to form
polynomial equations, which encode a wide range of problems, from elementary
word problems to complicated scientific problems; they are used to define polynomial functions, which appear in settings ranging from basic
chemistry
Chemistry is the scientific study of the properties and behavior of matter. It is a natural science that covers the elements that make up matter to the compounds made of atoms, molecules and ions: their composition, structure, properties, ...
and
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which relat ...
to
economics
Economics () is the social science that studies the production, distribution, and consumption of goods and services.
Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics analyzes ...
and
social science
Social science is one of the branches of science, devoted to the study of societies and the relationships among individuals within those societies. The term was formerly used to refer to the field of sociology, the original "science of soc ...
; they are used in
calculus and
numerical analysis to approximate other functions. In advanced mathematics, polynomials are used to construct
polynomial ring
In mathematics, especially in the field of algebra, a polynomial ring or polynomial algebra is a ring (which is also a commutative algebra) formed from the set of polynomials in one or more indeterminates (traditionally also called variabl ...
s and
algebraic varieties, which are central concepts in
algebra and
algebraic geometry
Algebraic geometry is a branch of mathematics, classically studying zeros of multivariate polynomials. Modern algebraic geometry is based on the use of abstract algebraic techniques, mainly from commutative algebra, for solving geometrical ...
.
Etymology
The word ''polynomial''
joins two diverse roots: the Greek ''poly'', meaning "many", and the Latin ''nomen'', or "name". It was derived from the term ''
binomial
Binomial may refer to:
In mathematics
* Binomial (polynomial), a polynomial with two terms
*Binomial coefficient, numbers appearing in the expansions of powers of binomials
* Binomial QMF, a perfectreconstruction orthogonal wavelet decomposition ...
'' by replacing the Latin root ''bi'' with the Greek ''poly''. That is, it means a sum of many terms (many
monomial
In mathematics, a monomial is, roughly speaking, a polynomial which has only one term. Two definitions of a monomial may be encountered:
# A monomial, also called power product, is a product of powers of variables with nonnegative integer expo ...
s). The word ''polynomial'' was first used in the 17th century.
Notation and terminology
The ''x'' occurring in a polynomial is commonly called a ''variable'' or an ''indeterminate''. When the polynomial is considered as an expression, ''x'' is a fixed symbol which does not have any value (its value is "indeterminate"). However, when one considers the
function defined by the polynomial, then ''x'' represents the argument of the function, and is therefore called a "variable". Many authors use these two words interchangeably.
A polynomial ''P'' in the indeterminate ''x'' is commonly denoted either as ''P'' or as ''P''(''x''). Formally, the name of the polynomial is ''P'', not ''P''(''x''), but the use of the
functional notation ''P''(''x'') dates from a time when the distinction between a polynomial and the associated function was unclear. Moreover, the functional notation is often useful for specifying, in a single phrase, a polynomial and its indeterminate. For example, "let ''P''(''x'') be a polynomial" is a shorthand for "let ''P'' be a polynomial in the indeterminate ''x''". On the other hand, when it is not necessary to emphasize the name of the indeterminate, many formulas are much simpler and easier to read if the name(s) of the indeterminate(s) do not appear at each occurrence of the polynomial.
The ambiguity of having two notations for a single mathematical object may be formally resolved by considering the general meaning of the functional notation for polynomials.
If ''a'' denotes a number, a variable, another polynomial, or, more generally, any expression, then ''P''(''a'') denotes, by convention, the result of substituting ''a'' for ''x'' in ''P''. Thus, the polynomial ''P'' defines the function
:
$a\backslash mapsto\; P(a),$
which is the ''polynomial function'' associated to ''P''.
Frequently, when using this notation, one supposes that ''a'' is a number. However, one may use it over any domain where addition and multiplication are defined (that is, any
ring
Ring may refer to:
* Ring (jewellery), a round band, usually made of metal, worn as ornamental jewelry
* To make a sound with a bell, and the sound made by a bell
:(hence) to initiate a telephone connection
Arts, entertainment and media Film and ...
). In particular, if ''a'' is a polynomial then ''P''(''a'') is also a polynomial.
More specifically, when ''a'' is the indeterminate ''x'', then the
image of ''x'' by this function is the polynomial ''P'' itself (substituting ''x'' for ''x'' does not change anything). In other words,
:
$P(x)=P,$
which justifies formally the existence of two notations for the same polynomial.
Definition
A ''polynomial expression'' is an
expression
Expression may refer to:
Linguistics
* Expression (linguistics), a word, phrase, or sentence
* Fixed expression, a form of words with a specific meaning
* Idiom, a type of fixed expression
* Metaphorical expression, a particular word, phrase, o ...
that can be built from
constants and symbols called ''variables'' or ''indeterminates'' by means of
addition
Addition (usually signified by the plus symbol ) is one of the four basic operations of arithmetic, the other three being subtraction, multiplication and division. The addition of two whole numbers results in the total amount or '' sum'' of ...
,
multiplication
Multiplication (often denoted by the cross symbol , by the midline dot operator , by juxtaposition, or, on computers, by an asterisk ) is one of the four elementary mathematical operations of arithmetic, with the other ones being addi ...
and
exponentiation
Exponentiation is a mathematical operation, written as , involving two numbers, the '' base'' and the ''exponent'' or ''power'' , and pronounced as " (raised) to the (power of) ". When is a positive integer, exponentiation corresponds to re ...
to a
nonnegative integer power. The constants are generally
number
A number is a mathematical object used to count, measure, and label. The original examples are the natural numbers 1, 2, 3, 4, and so forth. Numbers can be represented in language with number words. More universally, individual numbers ca ...
s, but may be any expression that do not involve the indeterminates, and represent
mathematical objects that can be added and multiplied. Two polynomial expressions are considered as defining the same ''polynomial'' if they may be transformed, one to the other, by applying the usual properties of
commutativity,
associativity
In mathematics, the associative property is a property of some binary operations, which means that rearranging the parentheses in an expression will not change the result. In propositional logic, associativity is a valid rule of replacemen ...
and
distributivity
In mathematics, the distributive property of binary operations generalizes the distributive law, which asserts that the equality
x \cdot (y + z) = x \cdot y + x \cdot z
is always true in elementary algebra.
For example, in elementary arithmeti ...
of addition and multiplication. For example
$(x1)(x2)$ and
$x^23x+2$ are two polynomial expressions that represent the same polynomial; so, one has the
equality
Equality may refer to:
Society
* Political equality, in which all members of a society are of equal standing
** Consociationalism, in which an ethnically, religiously, or linguistically divided state functions by cooperation of each group's elite ...
$(x1)(x2)=x^23x+2$.
A polynomial in a single indeterminate can always be written (or rewritten) in the form
:
$a\_n\; x^n\; +\; a\_x^\; +\; \backslash dotsb\; +\; a\_2\; x^2\; +\; a\_1\; x\; +\; a\_0,$
where
$a\_0,\; \backslash ldots,\; a\_n$ are constants that are called the ''coefficients'' of the polynomial, and
$x$ is the indeterminate.
The word "indeterminate" means that
$x$ represents no particular value, although any value may be substituted for it. The mapping that associates the result of this substitution to the substituted value is a
function, called a ''polynomial function''.
This can be expressed more concisely by using
summation notation:
:
$\backslash sum\_^n\; a\_k\; x^k$
That is, a polynomial can either be zero or can be written as the sum of a finite number of nonzero
terms. Each term consists of the product of a number called the
coefficient of the term and a finite number of indeterminates, raised to nonnegative integer powers.
Classification
The exponent on an indeterminate in a term is called the degree of that indeterminate in that term; the degree of the term is the sum of the degrees of the indeterminates in that term, and the degree of a polynomial is the largest degree of any term with nonzero coefficient.
Because , the degree of an indeterminate without a written exponent is one.
A term with no indeterminates and a polynomial with no indeterminates are called, respectively, a
constant term and a constant polynomial. The degree of a constant term and of a nonzero constant polynomial is 0. The degree of the zero polynomial 0 (which has no terms at all) is generally treated as not defined (but see below).
For example:
:
$5x^2y$
is a term. The coefficient is , the indeterminates are and , the degree of is two, while the degree of is one. The degree of the entire term is the sum of the degrees of each indeterminate in it, so in this example the degree is .
Forming a sum of several terms produces a polynomial. For example, the following is a polynomial:
:
$\backslash underbrace\_\; \backslash underbrace\_\; \backslash underbrace\_.$
It consists of three terms: the first is degree two, the second is degree one, and the third is degree zero.
Polynomials of small degree have been given specific names. A polynomial of degree zero is a ''constant polynomial'', or simply a ''constant''. Polynomials of degree one, two or three are respectively ''linear polynomials,'' ''
quadratic polynomials'' and ''cubic polynomials''.
[ For higher degrees, the specific names are not commonly used, although ''quartic polynomial'' (for degree four) and ''quintic polynomial'' (for degree five) are sometimes used. The names for the degrees may be applied to the polynomial or to its terms. For example, the term in is a linear term in a quadratic polynomial.
The polynomial 0, which may be considered to have no terms at all, is called the zero polynomial. Unlike other constant polynomials, its degree is not zero. Rather, the degree of the zero polynomial is either left explicitly undefined, or defined as negative (either −1 or −∞). The zero polynomial is also unique in that it is the only polynomial in one indeterminate that has an infinite number of ]roots
A root is the part of a plant, generally underground, that anchors the plant body, and absorbs and stores water and nutrients.
Root or roots may also refer to:
Art, entertainment, and media
* ''The Root'' (magazine), an online magazine focusing ...
. The graph of the zero polynomial, , is the ''x''axis.
In the case of polynomials in more than one indeterminate, a polynomial is called ''homogeneous'' of if ''all'' of its nonzero terms have . The zero polynomial is homogeneous, and, as a homogeneous polynomial, its degree is undefined. For example, is homogeneous of degree 5. For more details, see Homogeneous polynomial
In mathematics, a homogeneous polynomial, sometimes called quantic in older texts, is a polynomial whose nonzero terms all have the same degree. For example, x^5 + 2 x^3 y^2 + 9 x y^4 is a homogeneous polynomial of degree 5, in two variables; ...
.
The commutative law of addition can be used to rearrange terms into any preferred order. In polynomials with one indeterminate, the terms are usually ordered according to degree, either in "descending powers of ", with the term of largest degree first, or in "ascending powers of ". The polynomial is written in descending powers of . The first term has coefficient , indeterminate , and exponent . In the second term, the coefficient . The third term is a constant. Because the ''degree'' of a nonzero polynomial is the largest degree of any one term, this polynomial has degree two.
Two terms with the same indeterminates raised to the same powers are called "similar terms" or "like terms", and they can be combined, using the distributive law
In mathematics, the distributive property of binary operations generalizes the distributive law, which asserts that the equality
x \cdot (y + z) = x \cdot y + x \cdot z
is always true in elementary algebra.
For example, in elementary arithmetic, ...
, into a single term whose coefficient is the sum of the coefficients of the terms that were combined. It may happen that this makes the coefficient 0.[ Polynomials can be classified by the number of terms with nonzero coefficients, so that a oneterm polynomial is called a ]monomial
In mathematics, a monomial is, roughly speaking, a polynomial which has only one term. Two definitions of a monomial may be encountered:
# A monomial, also called power product, is a product of powers of variables with nonnegative integer expo ...
, a twoterm polynomial is called a binomial
Binomial may refer to:
In mathematics
* Binomial (polynomial), a polynomial with two terms
*Binomial coefficient, numbers appearing in the expansions of powers of binomials
* Binomial QMF, a perfectreconstruction orthogonal wavelet decomposition ...
, and a threeterm polynomial is called a ''trinomial''. The term "quadrinomial" is occasionally used for a fourterm polynomial.
A real polynomial is a polynomial with real coefficients. When it is used to define a function, the domain
Domain may refer to:
Mathematics
*Domain of a function, the set of input values for which the (total) function is defined
** Domain of definition of a partial function
** Natural domain of a partial function
** Domain of holomorphy of a function
* ...
is not so restricted. However, a real polynomial function is a function from the reals to the reals that is defined by a real polynomial. Similarly, an integer polynomial is a polynomial with integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the languag ...
coefficients, and a complex polynomial is a polynomial with complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
coefficients.
A polynomial in one indeterminate is called a ''univariate
In mathematics, a univariate object is an expression, equation, function or polynomial involving only one variable. Objects involving more than one variable are multivariate. In some cases the distinction between the univariate and multivariate ...
polynomial'', a polynomial in more than one indeterminate is called a multivariate polynomial. A polynomial with two indeterminates is called a bivariate polynomial.[ These notions refer more to the kind of polynomials one is generally working with than to individual polynomials; for instance, when working with univariate polynomials, one does not exclude constant polynomials (which may result from the subtraction of nonconstant polynomials), although strictly speaking, constant polynomials do not contain any indeterminates at all. It is possible to further classify multivariate polynomials as ''bivariate'', ''trivariate'', and so on, according to the maximum number of indeterminates allowed. Again, so that the set of objects under consideration be closed under subtraction, a study of trivariate polynomials usually allows bivariate polynomials, and so on. It is also common to say simply "polynomials in , and ", listing the indeterminates allowed.
The evaluation of a polynomial consists of substituting a numerical value to each indeterminate and carrying out the indicated multiplications and additions. For polynomials in one indeterminate, the evaluation is usually more efficient (lower number of arithmetic operations to perform) using Horner's method:
:$(((((a\_n\; x\; +\; a\_)x\; +\; a\_)x\; +\; \backslash dotsb\; +\; a\_3)x\; +\; a\_2)x\; +\; a\_1)x\; +\; a\_0.$
]
Arithmetic
Addition and subtraction
Polynomials can be added using the associative law
In mathematics, the associative property is a property of some binary operations, which means that rearranging the parentheses in an expression will not change the result. In propositional logic, associativity is a valid rule of replacement ...
of addition (grouping all their terms together into a single sum), possibly followed by reordering (using the commutative law) and combining of like terms. For example, if
:$P\; =\; 3x^2\; \; 2x\; +\; 5xy\; \; 2$ and $Q\; =\; 3x^2\; +\; 3x\; +\; 4y^2\; +\; 8$
then the sum
:$P\; +\; Q\; =\; 3x^2\; \; 2x\; +\; 5xy\; \; 2\; \; 3x^2\; +\; 3x\; +\; 4y^2\; +\; 8$
can be reordered and regrouped as
:$P\; +\; Q\; =\; (3x^2\; \; 3x^2)\; +\; (\; 2x\; +\; 3x)\; +\; 5xy\; +\; 4y^2\; +\; (8\; \; 2)$
and then simplified to
:$P\; +\; Q\; =\; x\; +\; 5xy\; +\; 4y^2\; +\; 6.$
When polynomials are added together, the result is another polynomial.
Subtraction of polynomials is similar.
Multiplication
Polynomials can also be multiplied. To expand the product
Product may refer to:
Business
* Product (business), an item that serves as a solution to a specific consumer problem.
* Product (project management), a deliverable or set of deliverables that contribute to a business solution
Mathematics
* Pr ...
of two polynomials into a sum of terms, the distributive law is repeatedly applied, which results in each term of one polynomial being multiplied by every term of the other.[ For example, if
:$\backslash begin\; \backslash color\; P\; \&\backslash color\; \backslash \backslash \; \backslash color\; Q\; \&\backslash color\; \backslash end$
then
:$\backslash begin\; \&\; \&\&(\backslash cdot)\; \&+\&(\backslash cdot)\&+\&(\backslash cdot\; )\&+\&(\backslash cdot)\; \backslash \backslash \&\&+\&(\backslash cdot)\&+\&(\backslash cdot)\&+\&(\backslash cdot\; )\&+\&\; (\backslash cdot)\; \backslash \backslash \&\&+\&(\backslash cdot)\&+\&(\backslash cdot)\&+\&\; (\backslash cdot\; )\&+\&(\backslash cdot)\; \backslash end$
Carrying out the multiplication in each term produces
:$\backslash begin\; PQ\; \&\; =\; \&\&\; 4x^2\; \&+\&\; 10xy\; \&+\&\; 2x^2y\; \&+\&\; 2x\; \backslash \backslash \; \&\&+\&\; 6xy\; \&+\&\; 15y^2\; \&+\&\; 3xy^2\; \&+\&\; 3y\; \backslash \backslash \; \&\&+\&\; 10x\; \&+\&\; 25y\; \&+\&\; 5xy\; \&+\&\; 5.\; \backslash end$
Combining similar terms yields
:$\backslash begin\; PQ\; \&\; =\; \&\&\; 4x^2\; \&+\&(\; 10xy\; +\; 6xy\; +\; 5xy\; )\; \&+\&\; 2x^2y\; \&+\&\; (\; 2x\; +\; 10x\; )\; \backslash \backslash \; \&\&\; +\; \&\; 15y^2\; \&+\&\; 3xy^2\; \&+\&(\; 3y\; +\; 25y\; )\&+\&5\; \backslash end$
which can be simplified to
:$PQ\; =\; 4x^2\; +\; 21xy\; +\; 2x^2y\; +\; 12x\; +\; 15y^2\; +\; 3xy^2\; +\; 28y\; +\; 5.$
As in the example, the product of polynomials is always a polynomial.][
]
Composition
Given a polynomial $f$ of a single variable and another polynomial of any number of variables, the composition
Composition or Compositions may refer to:
Arts and literature
*Composition (dance), practice and teaching of choreography
*Composition (language), in literature and rhetoric, producing a work in spoken tradition and written discourse, to include v ...
$f\; \backslash circ\; g$ is obtained by substituting each copy of the variable of the first polynomial by the second polynomial.[ For example, if $f(x)\; =\; x^2\; +\; 2x$ and $g(x)\; =\; 3x\; +\; 2$ then
$$(f\backslash circ\; g)(x)\; =\; f(g(x))\; =\; (3x\; +\; 2)^2\; +\; 2(3x\; +\; 2).$$
A composition may be expanded to a sum of terms using the rules for multiplication and division of polynomials. The composition of two polynomials is another polynomial.
]
Division
The division of one polynomial by another is not typically a polynomial. Instead, such ratios are a more general family of objects, called '' rational fractions'', ''rational expressions'', or '' rational functions'', depending on context. This is analogous to the fact that the ratio of two integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the languag ...
s is a rational number, not necessarily an integer. For example, the fraction is not a polynomial, and it cannot be written as a finite sum of powers of the variable .
For polynomials in one variable, there is a notion of Euclidean division of polynomials, generalizing the Euclidean division
In arithmetic, Euclidean division – or division with remainder – is the process of dividing one integer (the dividend) by another (the divisor), in a way that produces an integer quotient and a natural number remainder strictly smaller tha ...
of integers. This notion of the division results in two polynomials, a ''quotient'' and a ''remainder'' , such that and . The quotient and remainder may be computed by any of several algorithms, including polynomial long division
In algebra, polynomial long division is an algorithm for dividing a polynomial by another polynomial of the same or lower degree, a generalized version of the familiar arithmetic technique called long division. It can be done easily by hand, beca ...
and synthetic division.
When the denominator is monic and linear, that is, for some constant , then the polynomial remainder theorem asserts that the remainder of the division of by is the evaluation .[ In this case, the quotient may be computed by Ruffini's rule, a special case of synthetic division.
]
Factoring
All polynomials with coefficients in a unique factorization domain
In mathematics, a unique factorization domain (UFD) (also sometimes called a factorial ring following the terminology of Bourbaki) is a ring in which a statement analogous to the fundamental theorem of arithmetic holds. Specifically, a UFD is a ...
(for example, the integers or a field) also have a factored form in which the polynomial is written as a product of irreducible polynomial
In mathematics, an irreducible polynomial is, roughly speaking, a polynomial that cannot be factored into the product of two nonconstant polynomials. The property of irreducibility depends on the nature of the coefficients that are accepted f ...
s and a constant. This factored form is unique up to the order of the factors and their multiplication by an invertible constant. In the case of the field of complex number
In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= 1; every complex number can be expressed in the f ...
s, the irreducible factors are linear. Over the real numbers, they have the degree either one or two. Over the integers and the rational numbers the irreducible factors may have any degree. For example, the factored form of
:$5x^35$
is
:$5(x\; \; 1)\backslash left(x^2\; +\; x\; +\; 1\backslash right)$
over the integers and the reals, and
:$5(x\; \; 1)\backslash left(x\; +\; \backslash frac\backslash right)\backslash left(x\; +\; \backslash frac\backslash right)$
over the complex numbers.
The computation of the factored form, called ''factorization'' is, in general, too difficult to be done by handwritten computation. However, efficient polynomial factorization algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s are available in most computer algebra system
A computer algebra system (CAS) or symbolic algebra system (SAS) is any mathematical software with the ability to manipulate mathematical expressions in a way similar to the traditional manual computations of mathematicians and scientists. Th ...
s.
Calculus
Calculating derivative
In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. ...
s and integrals of polynomials is particularly simple, compared to other kinds of functions.
The derivative
In mathematics, the derivative of a function of a real variable measures the sensitivity to change of the function value (output value) with respect to a change in its argument (input value). Derivatives are a fundamental tool of calculus. ...
of the polynomial $$P\; =\; a\_n\; x^n\; +\; a\_\; x^\; +\; \backslash dots\; +\; a\_2\; x^2\; +\; a\_1\; x\; +\; a\_0\; =\; \backslash sum\_^n\; a\_i\; x^i$$ with respect to is the polynomial
$$n\; a\_n\; x^\; +\; (n\; \; 1)a\_\; x^\; +\; \backslash dots\; +\; 2\; a\_2\; x\; +\; a\_1\; =\; \backslash sum\_^n\; i\; a\_i\; x^.$$
Similarly, the general antiderivative
In calculus, an antiderivative, inverse derivative, primitive function, primitive integral or indefinite integral of a function is a differentiable function whose derivative is equal to the original function . This can be stated symbolic ...
(or indefinite integral) of $P$ is
$$\backslash frac\; +\; \backslash frac\; +\; \backslash dots\; +\; \backslash frac\; +\; \backslash frac\; +\; a\_0\; x\; +\; c\; =\; c\; +\; \backslash sum\_^n\; \backslash frac$$
where is an arbitrary constant. For example, antiderivatives of have the form .
For polynomials whose coefficients come from more abstract settings (for example, if the coefficients are integers modulo some prime number , or elements of an arbitrary ring), the formula for the derivative can still be interpreted formally, with the coefficient understood to mean the sum of copies of . For example, over the integers modulo , the derivative of the polynomial is the polynomial .
Polynomial functions
A ''polynomial function'' is a function that can be defined by evaluating a polynomial. More precisely, a function of one argument
An argument is a statement or group of statements called premises intended to determine the degree of truth or acceptability of another statement called conclusion. Arguments can be studied from three main perspectives: the logical, the dialec ...
from a given domain is a polynomial function if there exists a polynomial
:$a\_n\; x^n\; +\; a\_\; x^\; +\; \backslash cdots\; +\; a\_2\; x^2\; +\; a\_1\; x\; +\; a\_0$
that evaluates to $f(x)$ for all in the domain
Domain may refer to:
Mathematics
*Domain of a function, the set of input values for which the (total) function is defined
** Domain of definition of a partial function
** Natural domain of a partial function
** Domain of holomorphy of a function
* ...
of (here, is a nonnegative integer and are constant coefficients).
Generally, unless otherwise specified, polynomial functions have complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
coefficients, arguments, and values. In particular, a polynomial, restricted to have real coefficients, defines a function from the complex numbers to the complex numbers. If the domain of this function is also restricted to the reals, the resulting function is a real function that maps reals to reals.
For example, the function , defined by
:$f(x)\; =\; x^3\; \; x,$
is a polynomial function of one variable. Polynomial functions of several variables are similarly defined, using polynomials in more than one indeterminate, as in
:$f(x,y)=\; 2x^3+4x^2y+xy^5+y^27.$
According to the definition of polynomial functions, there may be expressions that obviously are not polynomials but nevertheless define polynomial functions. An example is the expression $\backslash left(\backslash sqrt\backslash right)^2,$ which takes the same values as the polynomial $1x^2$ on the interval $;\; href="/html/ALL/s/1,1.html"\; ;"title="1,1">1,1$continuous
Continuity or continuous may refer to:
Mathematics
* Continuity (mathematics), the opposing concept to discreteness; common examples include
** Continuous probability distribution or random variable in probability and statistics
** Continuous ...
, smooth
Smooth may refer to:
Mathematics
* Smooth function, a function that is infinitely differentiable; used in calculus and topology
* Smooth manifold, a differentiable manifold for which all the transition maps are smooth functions
* Smooth algebraic ...
, and entire
Entire may refer to:
* Entire function
In complex analysis, an entire function, also called an integral function, is a complexvalued function that is holomorphic on the whole complex plane. Typical examples of entire functions are polynomial ...
.
Graphs
File:Algebra1 fnz fig037 pc.svg, Polynomial of degree 0:
File:Fonction de Sophie Germain.png, Polynomial of degree 1:
File:Polynomialdeg2.svg, Polynomial of degree 2:
File:Polynomialdeg3.svg, Polynomial of degree 3:
File:Polynomialdeg4.svg, Polynomial of degree 4:
File:Quintic polynomial.svg, Polynomial of degree 5:
File:Sextic Graph.svg, Polynomial of degree 6:
File:Septic graph.svg, Polynomial of degree 7:
A polynomial function in one real variable can be represented by a graph
Graph may refer to:
Mathematics
* Graph (discrete mathematics), a structure made of vertices and edges
**Graph theory, the study of such graphs and their properties
* Graph (topology), a topological space resembling a graph in the sense of disc ...
.

The graph of the zero polynomial
is the axis.

The graph of a degree 0 polynomial
is a horizontal line with

The graph of a degree 1 polynomial (or linear function)
is an oblique line with and
slope
In mathematics, the slope or gradient of a line is a number that describes both the ''direction'' and the ''steepness'' of the line. Slope is often denoted by the letter ''m''; there is no clear answer to the question why the letter ''m'' is use ...
.

The graph of a degree 2 polynomial
is a parabola.

The graph of a degree 3 polynomial
is a cubic curve.

The graph of any polynomial with degree 2 or greater
is a continuous nonlinear curve.
A nonconstant polynomial function tends to infinity when the variable increases indefinitely (in absolute value
In mathematics, the absolute value or modulus of a real number x, is the nonnegative value without regard to its sign. Namely, , x, =x if is a positive number, and , x, =x if x is negative (in which case negating x makes x positive), and ...
). If the degree is higher than one, the graph does not have any asymptote. It has two parabolic branches with vertical direction (one branch for positive ''x'' and one for negative ''x'').
Polynomial graphs are analyzed in calculus using intercepts, slopes, concavity, and end behavior.
Equations
A ''polynomial equation'', also called an ''algebraic equation
In mathematics, an algebraic equation or polynomial equation is an equation of the form
:P = 0
where ''P'' is a polynomial with coefficients in some field, often the field of the rational numbers. For many authors, the term ''algebraic equation' ...
'', is an equation of the form
:$a\_n\; x^n\; +\; a\_x^\; +\; \backslash dotsb\; +\; a\_2\; x^2\; +\; a\_1\; x\; +\; a\_0\; =\; 0.$
For example,
:$3x^2\; +\; 4x\; 5\; =\; 0$
is a polynomial equation.
When considering equations, the indeterminates (variables) of polynomials are also called unknown
Unknown or The Unknown may refer to:
Film
* ''The Unknown'' (1915 comedy film), a silent boxing film
* ''The Unknown'' (1915 drama film)
* ''The Unknown'' (1927 film), a silent horror film starring Lon Chaney
* ''The Unknown'' (1936 film), a ...
s, and the ''solutions'' are the possible values of the unknowns for which the equality is true (in general more than one solution may exist). A polynomial equation stands in contrast to a ''polynomial identity'' like , where both expressions represent the same polynomial in different forms, and as a consequence any evaluation of both members gives a valid equality.
In elementary algebra, methods such as the quadratic formula
In elementary algebra, the quadratic formula is a formula that provides the solution(s) to a quadratic equation. There are other ways of solving a quadratic equation instead of using the quadratic formula, such as factoring (direct factoring, ...
are taught for solving all first degree and second degree polynomial equations in one variable. There are also formulas for the cubic
Cubic may refer to:
Science and mathematics
* Cube (algebra), "cubic" measurement
* Cube, a threedimensional solid object bounded by six square faces, facets or sides, with three meeting at each vertex
** Cubic crystal system, a crystal system w ...
and quartic equations. For higher degrees, the Abel–Ruffini theorem
In mathematics, the Abel–Ruffini theorem (also known as Abel's impossibility theorem) states that there is no solution in radicals to general polynomial equations of degree five or higher with arbitrary coefficients. Here, ''general'' means ...
asserts that there can not exist a general formula in radicals. However, rootfinding algorithms may be used to find numerical approximations of the roots of a polynomial expression of any degree.
The number of solutions of a polynomial equation with real coefficients may not exceed the degree, and equals the degree when the complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
solutions are counted with their multiplicity. This fact is called the fundamental theorem of algebra
The fundamental theorem of algebra, also known as d'Alembert's theorem, or the d'Alembert–Gauss theorem, states that every non constant singlevariable polynomial with complex coefficients has at least one complex root. This includes polynomia ...
.
Solving equations
A ''root'' of a nonzero univariate polynomial is a value of such that . In other words, a root of is a solution of the polynomial equation or a zero
0 (zero) is a number representing an empty quantity. In placevalue notation such as the Hindu–Arabic numeral system, 0 also serves as a placeholder numerical digit, which works by multiplying digits to the left of 0 by the radix, usu ...
of the polynomial function defined by . In the case of the zero polynomial, every number is a zero of the corresponding function, and the concept of root is rarely considered.
A number is a root of a polynomial if and only if the linear polynomial divides , that is if there is another polynomial such that . It may happen that a power (greater than ) of divides ; in this case, is a ''multiple root'' of , and otherwise is a simple root of . If is a nonzero polynomial, there is a highest power such that divides , which is called the ''multiplicity'' of as a root of . The number of roots of a nonzero polynomial , counted with their respective multiplicities, cannot exceed the degree of , and equals this degree if all complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
roots are considered (this is a consequence of the fundamental theorem of algebra
The fundamental theorem of algebra, also known as d'Alembert's theorem, or the d'Alembert–Gauss theorem, states that every non constant singlevariable polynomial with complex coefficients has at least one complex root. This includes polynomia ...
).
The coefficients of a polynomial and its roots are related by Vieta's formulas
In mathematics, Vieta's formulas relate the coefficients of a polynomial to sums and products of its roots. They are named after François Viète (more commonly referred to by the Latinised form of his name, "Franciscus Vieta").
Basic formula ...
.
Some polynomials, such as , do not have any roots among the real numbers. If, however, the set of accepted solutions is expanded to the complex number
In mathematics, a complex number is an element of a number system that extends the real numbers with a specific element denoted , called the imaginary unit and satisfying the equation i^= 1; every complex number can be expressed in the f ...
s, every nonconstant polynomial has at least one root; this is the fundamental theorem of algebra
The fundamental theorem of algebra, also known as d'Alembert's theorem, or the d'Alembert–Gauss theorem, states that every non constant singlevariable polynomial with complex coefficients has at least one complex root. This includes polynomia ...
. By successively dividing out factors , one sees that any polynomial with complex coefficients can be written as a constant (its leading coefficient) times a product of such polynomial factors of degree 1; as a consequence, the number of (complex) roots counted with their multiplicities is exactly equal to the degree of the polynomial.
There may be several meanings of "solving an equation". One may want to express the solutions as explicit numbers; for example, the unique solution of is . Unfortunately, this is, in general, impossible for equations of degree greater than one, and, since the ancient times, mathematicians have searched to express the solutions as algebraic expressions; for example, the golden ratio $(1+\backslash sqrt\; 5)/2$ is the unique positive solution of $x^2x1=0.$ In the ancient times, they succeeded only for degrees one and two. For quadratic equations, the quadratic formula
In elementary algebra, the quadratic formula is a formula that provides the solution(s) to a quadratic equation. There are other ways of solving a quadratic equation instead of using the quadratic formula, such as factoring (direct factoring, ...
provides such expressions of the solutions. Since the 16th century, similar formulas (using cube roots in addition to square roots), although much more complicated, are known for equations of degree three and four (see cubic equation
In algebra, a cubic equation in one variable is an equation of the form
:ax^3+bx^2+cx+d=0
in which is nonzero.
The solutions of this equation are called roots of the cubic function defined by the lefthand side of the equation. If all of t ...
and quartic equation). But formulas for degree 5 and higher eluded researchers for several centuries. In 1824, Niels Henrik Abel
Niels Henrik Abel ( , ; 5 August 1802 – 6 April 1829) was a Norwegian mathematician who made pioneering contributions in a variety of fields. His most famous single result is the first complete proof demonstrating the impossibility of solvin ...
proved the striking result that there are equations of degree 5 whose solutions cannot be expressed by a (finite) formula, involving only arithmetic operations and radicals (see Abel–Ruffini theorem
In mathematics, the Abel–Ruffini theorem (also known as Abel's impossibility theorem) states that there is no solution in radicals to general polynomial equations of degree five or higher with arbitrary coefficients. Here, ''general'' means ...
). In 1830, Évariste Galois
Évariste Galois (; ; 25 October 1811 – 31 May 1832) was a French mathematician and political activist. While still in his teens, he was able to determine a necessary and sufficient condition for a polynomial to be solvable by radicals, ...
proved that most equations of degree higher than four cannot be solved by radicals, and showed that for each equation, one may decide whether it is solvable by radicals, and, if it is, solve it. This result marked the start of Galois theory and group theory, two important branches of modern algebra. Galois himself noted that the computations implied by his method were impracticable. Nevertheless, formulas for solvable equations of degrees 5 and 6 have been published (see quintic function and sextic equation).
When there is no algebraic expression for the roots, and when such an algebraic expression exists but is too complicated to be useful, the unique way of solving it is to compute numerical approximations of the solutions. There are many methods for that; some are restricted to polynomials and others may apply to any continuous function. The most efficient algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s allow solving easily (on a computer
A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...
) polynomial equations of degree higher than 1,000 (see Rootfinding algorithm).
For polynomials with more than one indeterminate, the combinations of values for the variables for which the polynomial function takes the value zero are generally called ''zeros'' instead of "roots". The study of the sets of zeros of polynomials is the object of algebraic geometry
Algebraic geometry is a branch of mathematics, classically studying zeros of multivariate polynomials. Modern algebraic geometry is based on the use of abstract algebraic techniques, mainly from commutative algebra, for solving geometrical ...
. For a set of polynomial equations with several unknowns, there are algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
s to decide whether they have a finite number of complex
Complex commonly refers to:
* Complexity, the behaviour of a system whose components interact in multiple ways so possible interactions are difficult to describe
** Complex system, a system composed of many components which may interact with each ...
solutions, and, if this number is finite, for computing the solutions. See System of polynomial equations.
The special case where all the polynomials are of degree one is called a system of linear equations
In mathematics, a system of linear equations (or linear system) is a collection of one or more linear equations involving the same variables.
For example,
:\begin
3x+2yz=1\\
2x2y+4z=2\\
x+\fracyz=0
\end
is a system of three equations in t ...
, for which another range of different solution methods exist, including the classical Gaussian elimination.
A polynomial equation for which one is interested only in the solutions which are integer
An integer is the number zero (), a positive natural number (, , , etc.) or a negative integer with a minus sign (−1, −2, −3, etc.). The negative numbers are the additive inverses of the corresponding positive numbers. In the languag ...
s is called a Diophantine equation. Solving Diophantine equations is generally a very hard task. It has been proved that there cannot be any general algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
for solving them, or even for deciding whether the set of solutions is empty (see Hilbert's tenth problem). Some of the most famous problems that have been solved during the last fifty years are related to Diophantine equations, such as Fermat's Last Theorem.
Polynomial expressions
Polynomials where indeterminates are substituted for some other mathematical objects are often considered, and sometimes have a special name.
Trigonometric polynomials
A trigonometric polynomial is a finite linear combination of functions sin(''nx'') and cos(''nx'') with ''n'' taking on the values of one or more natural numbers. The coefficients may be taken as real numbers, for realvalued functions.
If sin(''nx'') and cos(''nx'') are expanded in terms of sin(''x'') and cos(''x''), a trigonometric polynomial becomes a polynomial in the two variables sin(''x'') and cos(''x'') (using List of trigonometric identities#Multipleangle formulae). Conversely, every polynomial in sin(''x'') and cos(''x'') may be converted, with Producttosum identities, into a linear combination of functions sin(''nx'') and cos(''nx''). This equivalence explains why linear combinations are called polynomials.
For complex coefficients, there is no difference between such a function and a finite Fourier series.
Trigonometric polynomials are widely used, for example in trigonometric interpolation applied to the interpolation of periodic functions. They are also used in the discrete Fourier transform
In mathematics, the discrete Fourier transform (DFT) converts a finite sequence of equallyspaced samples of a function into a samelength sequence of equallyspaced samples of the discretetime Fourier transform (DTFT), which is a comple ...
.
Matrix polynomials
A matrix polynomial is a polynomial with square matrices as variables. Given an ordinary, scalarvalued polynomial
:$P(x)\; =\; \backslash sum\_^n\; =a\_0\; +\; a\_1\; x+\; a\_2\; x^2\; +\; \backslash cdots\; +\; a\_n\; x^n,$
this polynomial evaluated at a matrix ''A'' is
:$P(A)\; =\; \backslash sum\_^n\; =a\_0\; I\; +\; a\_1\; A\; +\; a\_2\; A^2\; +\; \backslash cdots\; +\; a\_n\; A^n,$
where ''I'' is the identity matrix
In linear algebra, the identity matrix of size n is the n\times n square matrix with ones on the main diagonal and zeros elsewhere.
Terminology and notation
The identity matrix is often denoted by I_n, or simply by I if the size is immaterial or ...
.
A matrix polynomial equation is an equality between two matrix polynomials, which holds for the specific matrices in question. A matrix polynomial identity is a matrix polynomial equation which holds for all matrices ''A'' in a specified matrix ring ''M_{n}''(''R'').
Exponential polynomials
A bivariate polynomial where the second variable is substituted for an exponential function applied to the first variable, for example , may be called an exponential polynomial.
Related concepts
Rational functions
A rational fraction is the quotient ( algebraic fraction) of two polynomials. Any algebraic expression In mathematics, an algebraic expression is an expression built up from integer constants, variables, and the algebraic operations (addition, subtraction, multiplication, division and exponentiation by an exponent that is a rational number). For ...
that can be rewritten as a rational fraction is a rational function.
While polynomial functions are defined for all values of the variables, a rational function is defined only for the values of the variables for which the denominator is not zero.
The rational fractions include the Laurent polynomials, but do not limit denominators to powers of an indeterminate.
Laurent polynomials
Laurent polynomials are like polynomials, but allow negative powers of the variable(s) to occur.
Power series
Formal power series
In mathematics, a formal series is an infinite sum that is considered independently from any notion of convergence, and can be manipulated with the usual algebraic operations on series (addition, subtraction, multiplication, division, partial s ...
are like polynomials, but allow infinitely many nonzero terms to occur, so that they do not have finite degree. Unlike polynomials they cannot in general be explicitly and fully written down (just like irrational numbers cannot), but the rules for manipulating their terms are the same as for polynomials. Nonformal power series also generalize polynomials, but the multiplication of two power series may not converge.
Polynomial ring
A ''polynomial'' over a commutative ring
In mathematics, a commutative ring is a ring in which the multiplication operation is commutative. The study of commutative rings is called commutative algebra. Complementarily, noncommutative algebra is the study of ring properties that are not s ...
is a polynomial all of whose coefficients belong to . It is straightforward to verify that the polynomials in a given set of indeterminates over form a commutative ring, called the ''polynomial ring'' in these indeterminates, denoted $R;\; href="/html/ALL/s/.html"\; ;"title="">$ring homomorphism
In ring theory, a branch of abstract algebra, a ring homomorphism is a structurepreserving function between two rings. More explicitly, if ''R'' and ''S'' are rings, then a ring homomorphism is a function such that ''f'' is:
:addition preser ...
, by which is viewed as a subring of . In particular, is an algebra over .
One can think of the ring as arising from by adding one new element ''x'' to ''R'', and extending in a minimal way to a ring in which satisfies no other relations than the obligatory ones, plus commutation with all elements of (that is ). To do this, one must add all powers of and their linear combinations as well.
Formation of the polynomial ring, together with forming factor rings by factoring out ideals, are important tools for constructing new rings out of known ones. For instance, the ring (in fact field) of complex numbers, which can be constructed from the polynomial ring over the real numbers by factoring out the ideal of multiples of the polynomial . Another example is the construction of finite fields, which proceeds similarly, starting out with the field of integers modulo some prime number as the coefficient ring (see modular arithmetic).
If is commutative, then one can associate with every polynomial in a ''polynomial function'' with domain and range equal to . (More generally, one can take domain and range to be any same unital associative algebra
In mathematics, an associative algebra ''A'' is an algebraic structure with compatible operations of addition, multiplication (assumed to be associative), and a scalar multiplication by elements in some field ''K''. The addition and multipli ...
over .) One obtains the value by substitution
Substitution may refer to:
Arts and media
* Chord substitution, in music, swapping one chord for a related one within a chord progression
* Substitution (poetry), a variation in poetic scansion
* "Substitution" (song), a 2009 song by Silversun P ...
of the value for the symbol in . One reason to distinguish between polynomials and polynomial functions is that, over some rings, different polynomials may give rise to the same polynomial function (see Fermat's little theorem
Fermat's little theorem states that if ''p'' is a prime number, then for any integer ''a'', the number a^p  a is an integer multiple of ''p''. In the notation of modular arithmetic, this is expressed as
: a^p \equiv a \pmod p.
For example, if = ...
for an example where is the integers modulo ). This is not the case when is the real or complex numbers, whence the two concepts are not always distinguished in analysis. An even more important reason to distinguish between polynomials and polynomial functions is that many operations on polynomials (like Euclidean division
In arithmetic, Euclidean division – or division with remainder – is the process of dividing one integer (the dividend) by another (the divisor), in a way that produces an integer quotient and a natural number remainder strictly smaller tha ...
) require looking at what a polynomial is composed of as an expression rather than evaluating it at some constant value for .
Divisibility
If is an integral domain and and are polynomials in , it is said that ''divides'' or is a divisor of if there exists a polynomial in such that . If $a\backslash in\; R,$ then is a root of if and only $xa$ divides . In this case, the quotient can be computed using the polynomial long division
In algebra, polynomial long division is an algorithm for dividing a polynomial by another polynomial of the same or lower degree, a generalized version of the familiar arithmetic technique called long division. It can be done easily by hand, beca ...
.
If is a field and and are polynomials in with , then there exist unique polynomials and in with
:$f\; =\; q\; \backslash ,\; g\; +\; r$
and such that the degree of is smaller than the degree of (using the convention that the polynomial 0 has a negative degree). The polynomials and are uniquely determined by and . This is called ''Euclidean division
In arithmetic, Euclidean division – or division with remainder – is the process of dividing one integer (the dividend) by another (the divisor), in a way that produces an integer quotient and a natural number remainder strictly smaller tha ...
, division with remainder'' or ''polynomial long division'' and shows that the ring is a Euclidean domain
In mathematics, more specifically in ring theory, a Euclidean domain (also called a Euclidean ring) is an integral domain that can be endowed with a Euclidean function which allows a suitable generalization of the Euclidean division of integer ...
.
Analogously, ''prime polynomials'' (more correctly, ''irreducible polynomial
In mathematics, an irreducible polynomial is, roughly speaking, a polynomial that cannot be factored into the product of two nonconstant polynomials. The property of irreducibility depends on the nature of the coefficients that are accepted f ...
s'') can be defined as ''nonzero polynomials which cannot be factorized into the product of two nonconstant polynomials''. In the case of coefficients in a ring, ''"nonconstant"'' must be replaced by ''"nonconstant or nonunit
Unit may refer to:
Arts and entertainment
* UNIT, a fictional military organization in the science fiction television series ''Doctor Who''
* Unit of action, a discrete piece of action (or beat) in a theatrical presentation
Music
* ''Unit'' (a ...
"'' (both definitions agree in the case of coefficients in a field). Any polynomial may be decomposed into the product of an invertible constant by a product of irreducible polynomials. If the coefficients belong to a field or a unique factorization domain
In mathematics, a unique factorization domain (UFD) (also sometimes called a factorial ring following the terminology of Bourbaki) is a ring in which a statement analogous to the fundamental theorem of arithmetic holds. Specifically, a UFD is a ...
this decomposition is unique up to the order of the factors and the multiplication of any nonunit factor by a unit (and division of the unit factor by the same unit). When the coefficients belong to integers, rational numbers or a finite field, there are algorithms to test irreducibility and to compute the factorization into irreducible polynomials (see Factorization of polynomials
In mathematics and computer algebra, factorization of polynomials or polynomial factorization expresses a polynomial with coefficients in a given field or in the integers as the product of irreducible factors with coefficients in the same doma ...
). These algorithms are not practicable for handwritten computation, but are available in any computer algebra system
A computer algebra system (CAS) or symbolic algebra system (SAS) is any mathematical software with the ability to manipulate mathematical expressions in a way similar to the traditional manual computations of mathematicians and scientists. Th ...
. Eisenstein's criterion
In mathematics, Eisenstein's criterion gives a sufficient condition for a polynomial with integer coefficients to be irreducible over the rational numbers – that is, for it to not be factorizable into the product of nonconstant polynomials with ...
can also be used in some cases to determine irreducibility.
Applications
Positional notation
In modern positional numbers systems, such as the decimal system, the digits and their positions in the representation of an integer, for example, 45, are a shorthand notation for a polynomial in the radix or base, in this case, . As another example, in radix 5, a string of digits such as 132 denotes the (decimal) number = 42. This representation is unique. Let ''b'' be a positive integer greater than 1. Then every positive integer ''a'' can be expressed uniquely in the form
:$a\; =\; r\_m\; b^m\; +\; r\_\; b^\; +\; \backslash dotsb\; +\; r\_1\; b\; +\; r\_0,$
where ''m'' is a nonnegative integer and the ''rs are integers such that
: and for .
Interpolation and approximation
The simple structure of polynomial functions makes them quite useful in analyzing general functions using polynomial approximations. An important example in calculus is Taylor's theorem, which roughly states that every differentiable function locally looks like a polynomial function, and the Stone–Weierstrass theorem, which states that every continuous function defined on a compact interval of the real axis can be approximated on the whole interval as closely as desired by a polynomial function. Practical methods of approximation include polynomial interpolation and the use of splines.
Other applications
Polynomials are frequently used to encode information about some other object. The characteristic polynomial
In linear algebra, the characteristic polynomial of a square matrix is a polynomial which is invariant under matrix similarity and has the eigenvalues as roots. It has the determinant and the trace of the matrix among its coefficients. The ch ...
of a matrix or linear operator contains information about the operator's eigenvalues. The minimal polynomial of an algebraic element records the simplest algebraic relation satisfied by that element. The chromatic polynomial of a graph
Graph may refer to:
Mathematics
* Graph (discrete mathematics), a structure made of vertices and edges
**Graph theory, the study of such graphs and their properties
* Graph (topology), a topological space resembling a graph in the sense of disc ...
counts the number of proper colourings of that graph.
The term "polynomial", as an adjective, can also be used for quantities or functions that can be written in polynomial form. For example, in computational complexity theory
In theoretical computer science and mathematics, computational complexity theory focuses on classifying computational problems according to their resource usage, and relating these classes to each other. A computational problem is a task solved by ...
the phrase ''polynomial time
In computer science, the time complexity is the computational complexity that describes the amount of computer time it takes to run an algorithm. Time complexity is commonly estimated by counting the number of elementary operations performed by ...
'' means that the time it takes to complete an algorithm
In mathematics and computer science, an algorithm () is a finite sequence of rigorous instructions, typically used to solve a class of specific problems or to perform a computation. Algorithms are used as specifications for performing ...
is bounded by a polynomial function of some variable, such as the size of the input.
History
Determining the roots of polynomials, or "solving algebraic equations", is among the oldest problems in mathematics. However, the elegant and practical notation we use today only developed beginning in the 15th century. Before that, equations were written out in words. For example, an algebra problem from the Chinese Arithmetic in Nine Sections, circa 200 BCE, begins "Three sheafs of good crop, two sheafs of mediocre crop, and one sheaf of bad crop are sold for 29 dou." We would write .
History of the notation
The earliest known use of the equal sign is in Robert Recorde's ''The Whetstone of Witte
''The Whetstone of Witte'' is the shortened title of Robert Recorde's mathematics book published in 1557, the full title being ''The whetstone of , is the : The ''Coßike'' practise, with the rule of ''Equation'': and the of ''Surde Nombers. ...
'', 1557. The signs + for addition, − for subtraction, and the use of a letter for an unknown appear in Michael Stifel
Michael Stifel or Styfel (1487 – April 19, 1567) was a German monk, Protestant reformer and mathematician. He was an Augustinian who became an early supporter of Martin Luther. He was later appointed professor of mathematics at Jena Univer ...
's ''Arithemetica integra'', 1544. René Descartes, in ''La géometrie'', 1637, introduced the concept of the graph of a polynomial equation. He popularized the use of letters from the beginning of the alphabet to denote constants and letters from the end of the alphabet to denote variables, as can be seen above, in the general formula for a polynomial in one variable, where the 's denote constants and denotes a variable. Descartes introduced the use of superscripts to denote exponents as well.
See also
* List of polynomial topics
Notes
References
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*. This classical book covers most of the content of this article.
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External links
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Algebra