1. The problem statement, all variables and given/known data Find the sum of sigma (n=1 to infinity) (-1)^(n-1) * [n/(4^(n-1))] using the power series 1/(1+x) = sigma (n=0 to infinity) (-1)^n * x^n. 2. Relevant equations 1/(1+x) = 1 - x + x^2 - x^3 + x^4 + ... + (-1)^n * x^n 3. The attempt at a solution The problem suggested to differentiate both sides and then substitute 1/4 for x. I am totally confused and don't even know where to begin.