# CIE A Level Maths: Pure 3复习笔记4.1.2 Product Rule

### Product Rule

#### What is the product rule?

• The product rule is a formula that allows you to differentiate a product of two functions

#### Exam Tip

• The product rule formulae are in the formulae booklet – make sure you know how to find them.
• Don't confuse the product of two functions with a composite function:
• The product of two functions is two functions multiplied together
• composite function is a function of a function

• To differentiate composite functions you need to use the chain rule