So, I'm trying to find the derivative of f(x)=3/x. I know, using the power rule, that the derivative is -3x^-2 (or -3/x^2). However, I need to solve the problem using the f'(x)=[f(x+h)-f(x)]/h formula. Here is my work so far: f'(x)=[(3/x+h)-(3/x) Make common denominator of x(x+h) f'(x)=[3x/x(x+h)]-[(3(x+h))/x(x+h)] Simplify f'(x)=[3x/x(x+h)]-[(3x+3h)/x(x+h)] f'(x)=(3x-3x-3h)/x(x+h) f'(x)=-3h/x(x+h) That is where I loose it. I see that I can make the denominator (x^2)+hx, but that is about as far as I can get. Any help with this is appreciated. Its probably just my algebra failing me or a dumb mistake. Thanks for the help!