1. The problem statement, all variables and given/known data f(x) = (x) / (x + (c/x) ) 2. Relevant equations Product rule and quotient rule 3. The attempt at a solution f'(x) = [ (x + (c/x)) - (x(1-(c/x^2)) ] / [ (s + (c/x)^2) ] = [x + (c/x) - x + (c/x)] / [(x+(c/x)^2)] = [2c/x] / [(x + (c/x)^2)] That's where I'm stuck. I need to brush up on algebra, I know. If anyone can give me any good review sites, that'd be great. I'm just doing problems in the book in my own time, and this is an odd number. The answer is: [2cx] / [ (9x^2)+c)^2 ] Was I even going along in the right direction? I also tried doing it as simply a product rule, where I just made it cx^-1, but that got messy when I tried to simplify.