Mathematics Archives
Math Archives: Visual Calculus: Functions
Use this site to find the defintion of a function. The site offers a discussion on the vertical line test, symbolic, numerical and verbal discussions on the definition of a function.
Curated OER
Mathn stuff.com: Vertical Line Test
Defines the vertical line test and provides a diagram showing graphs which pass and fail the test. Also provides several links for further information.
Windstream
Ojk's Precalculus Study Page: Functions
An introduction to the basic terminology of functions, including how to use the vertical line test on the graph of a relation as a means of testing whether or not it is a function.