Function definition:
In mathematics, a function is a relation between a set of inputs and a set of permissible outputs with the property that each input is related to exactly one output. An example is the function that relates each real number x to its square x². The output of a function f corresponding to an input x is denoted by f(x) (read "f of x").
Function table of values:
x y
2 10
3 15
4 20
5 25
P.S. Sorry, this is a bad answer. Don't have much time...
