1. The problem statement, all variables and given/known data For each n, let y^(n) denote the nth derivative of the function y = e^(x) cosx. Can you suggest a general formula for y^(k), where k is an interger > 0? What is y^(2010)? 2. Relevant equations None 3. The attempt at a solution I got e^(x) (cosx - sinx) for y' -2e^(x) sinx for y'' -2e^(x) (cosx + sinx) for y''' and -4e^(x) cosx for y'''' which are right, but I dont see a pattern for the nth derivative, which could help me answer the question.