froston

Hello. This is a question on my latest Calculus assignment: Let f: R --> R be a function, and let a not equal zero. Suppose f is differentiable at a. Evaluate the following limit: lim x-->a of (see attached image). Express your answer in terms of f'(a). Basically I'm having trouble understanding the third roots in the denominator, and how I am supposed to tackle this question. Any push in the right direction would be greatly appreciated.