AQA A Level Maths: Pure复习笔记7.2.3 Second Order Derivatives

Second Order Derivatives

What is the second order derivative of a function?

  • If you differentiate the derivative of a function (ie differentiate the function a second time) you get the second order derivative of the function
  • For a function y = f(x), there are two forms of notation for the second derivative (or second order derivative)
    • Note the positions of the power of 2's in the second version

7.2.3-2nd-Order-Deriv-Illustr-2

  • The second order derivative can also be referred to simply as the second derivative
    • Similarly, the 'regular' derivative can also be referred to as either the first order derivative or the first derivative
  • The second order derivative gives the rate of change of the gradient function (ie of the first derivative) – this will be important for identifying the nature of stationary points

Exam Tip

  • When finding second derivatives be especially careful with functions that have negative or fractional powers of x (see Worked Example below).
  • Mistakes made with fractions or negative signs can build up as you calculate the derivative more than once.

Worked Example

7.2.3-2nd-Order-Deriv-Example

 

 

 

 

 

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