1. The problem statement, all variables and given/known data Use the definition of the derivative to find f'(x) is f(x)=(12)/(sqrt(1+3x)) 2. Relevant equations I have a feeling you use some conjugate techniques, but I'm stuck. f'(x)=lim h->0 (f(x+h) - f(x))/(h) 3. The attempt at a solution I could post a very long list of useless equations, but that would be wasting time. I don't know how to do this or where to start, since I know what I'm doing is not the correct way to start. I know what the answer is using the quotient and power rules, but they want you to use the definition of the derivative. So, the start would be to state that lim h->0 (f(x+h) - f(x))/(h), but there's algebra involved that I'm missing. Anyone want to help?