Please help! I just can't get through this problem and I really need someone to tell me what I need to do.

The problem is as follows f(x) 1/ (root)x; and we're using the formula of limit as delta x approaches 0; of f(x+deltax) - f(x) / (all over) delta x.; I'm unsure of how to start this problem, so any help would be so useful! thank you!!