Prove summation of nx^n=x/(1-x)^2,ranging from zero to ifinity,using sum of Geometry progression?

You don't say what set of numbers n and x belong to. Usually it'd be something like positive integers. To prove for a positive integer, you need to prove it is true for n=1, x=1 and then prove it is true for n+1, x+1. But because this could be positive or negative, rational or irrational, integer, transcendental, real, imaginary or complex numbers, standard ways of solving it are difficult to apply.