Product Rule (Cambridge (CIE) AS Maths: Pure 2): Revision Note

Exam code: 9709

Product rule

What is the product rule?

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

  • If y=u×v where u and v are functions of x then the product rule is:

dydx=udvdx+vdudx

  • In function notation, if f(x)=g(x)×h(x) then the product rule can be written as:

f'(x)=g(x)h'(x)+h(x)g'(x)

     

  • The easiest way to remember the product rule is, for y=u×v where u and v are functions of x:

y' = uv' + vu'

Product Rule Eg, AS & A Level Maths revision notes

 

Examiner Tips and Tricks

  • 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

    • A composite function is a function of a function

 

Product Rule Prod Comp Illustr, AS & A Level Maths revision notes

 

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

Worked Example

Product Rule Example, A Level & AS Level Pure Maths Revision Notes

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