Edexcel A Level Maths: Pure:复习笔记10.1.1 Change of Sign
Change of Sign
What does a change of sign mean?
- A sign change between f(a) to f(b) means there must be a root between a and b
- When an equation cannot be solved using the usual analytical methods, we can use change of sign to find approximate solutions
- We can say a root lies within a particular interval or is correct to a given accuracy
- Bounds can be used to show a root is correct
- Using sign change to find a root is only appropriate for continuous functions in a small interval
Exam Tip
- Remember this will only work if the function is continuous and the interval is small enough.
- Sign change questions may be part of bigger numerical methods questions.
Worked Example
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