Question

find the derivative of f(x) = 8/x at x = -1.

Answer 1

does it just mean to plug in -1 for x or do I have to use the derivative formula?

Answer 2

8 is a constant so forget it for a while. The derivative of 1/x is -1/x^2. evaluated at -1 the answer is -8

Answer 3

Take the derivative first then plug in -1

Answer 4

is there a site where i can find the derivatives?

Answer 5

nevermind I found one, thank you very much :)