Instead of drawing boxes all the time, we need a way to talk about functions with math symbols.

Let's take a look at a couple of the boxes in our last lesson:

THE RULE:  Add 1

domain guys go in  ->  rule: + 1  ->  range guys spit out

If we use x to represent our domain guys, here's the official notation:

f( x ) = x + 1  ...  f( x) is the input  ...  x + 1 is the output

(You read this guy, f(x), as "f of x.")

x guys go in... and x + 1 guys spit out.

But, x + 1 = f( x ) ...