# Composition of Functions

Let and .
The

**composite function**uses the output of as input to . For example, if then the output of would be . We plug this output 16 into to get The composite function is also sometimes written as . We say this out loud as "*f of g of x.*" Here's another example: Let and . Then, . The formula for is . Answer the multiple choice questions below to test your understanding of the composition of functions. Then move on to the next page of this GeoGebra book.Let and . What is

What is the formula for ?

If you're still confused about the composition of functions, you might read the following article on Math is Fun.
https://www.mathsisfun.com/sets/functions-composition.html