Question

What does it mean to evaluate a function?

Answer 1

http://www.mathsisfun.com/algebra/functions-evaluating.html

Answer 2

What does it mean to evaluate a function?
To evaluate a function means to pick different values for the input (often named x) in order to find the output (often named y). In terms of evaluation, for every choice of x that you pick, only one corresponding value of y will be the end result. You'll often be directed to evaluate a particular function for a certain value of x