1. The problem statement, all variables and given/known data Find d^2y/dx^2. y = x cos x 3. The attempt at a solution I've been doing derivatives recently and now got into doing them with trig functions. I thought it was, y = x cos x = -xsinx = -xcosx but that is the derivative of the derivative. The problem asks for d^2/dx^2. Can someone explain what to do in this situation? What is the difference of dx/dy, d^2y/dx^2, dy^2/d^2x, etc.... Please and thank you.