Question

find the derivative of f(x)=-9/x at x=-8

Answer 1

Have you learned your shortcuts for taking derivatives yet?
Or should we use the `Limit Definition for the Derivative`?

Answer 2

I haven't learned the shortcuts yet

Answer 3

isn't it 9/64 ?

Answer 4

Using the limit definition:
\[\large f'(-8)=\frac{\dfrac{-9}{-8+h}-\dfrac{-9}{-8}}{h}\]

Which simplifies toooo, yah 9/64 sounds right, good job.

Answer 5

thank you!(: