One-to-One Function

In a one-to-one function, each x-value has only one y-value, and each y-value has only one x-value. That is, different values of the domain correspond to different values of the range.

Example 1

Determine if the relation given is one-to-one.

Horizontal Line Test

A function is one-to-one if every horizontal line intersects the graph of the function at most once. (Note:  It is a function, so it also must pass the vertical line test.)

Example 2

Determine if the relation given is one-to-one.