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
