Concept
Version 9
Created by Boundless
One-to-One Functions

Horizontal Line Test
Because the horizontal line crosses the graph of the function more than once, it fails the horizontal line test and cannot be one-to-one.
Horizontal line test fail.
Source
Boundless vets and curates high-quality, openly licensed content from around the Internet. This particular resource used the following sources:
"Horizontal-test-fail.png."
https://upload.wikimedia.org/wikipedia/commons/f/f9/Horizontal-test-fail.png?uselang=en-ca
Wikipedia
CC BY-SA 3.0.