**Function notation** is a common way to write equations. Function notation is written and read “f of x.” When we are dealing with functions it is enough to say . and are pretty much interchangeable, but there are few things that function notation allows us to do that a regular doesn’t.

Another perk of using function notation is that you can plug things into the function really easily. If we want to find out when we will write

You can also plug in other variables. To plug these

- Put a set of parenthesis wherever was
- Then plug your variable/expression into the parenthesis
- Simplify

What you plug into the equation, your values, are called *domain*. The values you get out of the equation, either or are called *range*.