1. The problem statement, all variables and given/known data Find all polynomials P(x), such that P(x² - 2x) = [P(x-2)]² 2. Relevant equations Polynomial equations 3. The attempt at a solution Let x = y+2, then P(y²+2y) = P²(y) I tried to analyse by derivating P'(y²+2y)(2y+2) = 2P(y)P'(y) P'(y²+2y)(y+1) = P'(y)P(y) I am not sure if I derivated correctly, though Yet, that's it. Any ideas?