The composite rule is also known as the chain rule. Put simply, the derivative of the inside times the derivative of the outside.
Where
The inside, u, is:
Find the derivative of this and get
. And we know the derivative of , so we have:
In case that was too complicated for you, the following example might be easier. The principle is the same - the derivative of a function is the derivative of the outside times the derivative of the inside.
Suppose you want to take the derivative of
Then your answer is