horizontal line test
[horizontal line test|horizontal line test] The horizontal line test is a method used to determine if a graph represents a one-to-one function by checking whether any horizontal line intersects the graph more than once.
Definition
horizontal line test The horizontal line test is a method used to determine if a graph represents a one-to-<a href='/en/entity/one-function'>one function</a> by checking whether any horizontal line intersects the graph more than once.
Mechanism
horizontal line test Restricting the domain to [ 0 , ∞ ) makes the function one-to-one, which allows it to pass the horizontal line test and have an inverse on this restricted domain. The horizontal line test is used to verify if a graph represents a one-to-<a href='/en/entity/one-function'>one function</a>.
Examples
horizontal line test The horizontal line test is used to determine if a function is one-to-one. For example, the square function f(x) = x^2 with domain restricted to [0, ∞) passes the horizontal line test and has an inverse.