f(x). "f(x) = ... " is the classic way of writing a function. And there are other ways, as you will see! .... Example: {(2, 4), (2,5), (7,3)} is not a function because {2,4} and {2,5} means that 2 could be related to .
This is a function because no x-values repeat. If you were to graph all these numbers and then do the vertical line test it would pass because none of the x-values repeat.
