1. The problem statement, all variables and given/known data It's been a while since I've done derivatives. I'm working on a physics problem and can't seem to get the correct derivate for a function of the following form: f(x)= A [1+9x^2(x-4)^2]^1/2 A is a constant. 3. The attempt at a solution I've tried various ways of deriving. Silly. But nothing works for the physics problem I am working with. I derived the whole radical. Brought down the 1/2 and was left with the what's inside the radical raised to -1/2 and then deriving the inside. I believe my final derivative is in terms of A and x. Any tips on how to derive this function?