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In mathematics, the vertical line test is a visual way to determine if a
In mathematics, the vertical line test is a visual way to determine if a curve
In mathematics, a curve (also called a curved line in older texts) is an object similar to a line, but that does not have to be straight.
Intuitively, a curve may be thought of as the trace left by a moving point. This is the definition that ...
is a graph of a function or not. A function
Function or functionality may refer to:
Computing
* Function key, a type of key on computer keyboards
* Function model, a structured representation of processes in a system
* Function object or functor or functionoid, a concept of object-oriente ...
can only have one output, ''y'', for each unique input, ''x''. If a vertical line intersects a curve on an ''xy''-plane more than once then for one value of ''x'' the curve has more than one value of ''y'', and so, the curve does not represent a function. If all vertical lines intersect a curve at most once then the curve represents a function.
See also
*Horizontal line test
In mathematics, the horizontal line test is a test used to determine whether a function is injective (i.e., one-to-one).
In calculus
A ''horizontal line'' is a straight, flat line that goes from left to right. Given a function f \colon \mathbb \t ...
Notes
{{Reflist Functions and mappings