I am having trouble with the following problem.

Let f(x) = cubedroot of x

if a is not equal to 0, use f`(a) = lim as x approaches a {f(x)-f(a)}/(x-a) to find f`(a)

I put it as lim as h approaches 0 (cubed root (a+h)-cubed root (a))/h but am unsure if this is correct and what I should do next.

Thanks