Hi,

This math problem is really confusing me, any ideas on how to start?

i have to explicitely compute the function f defined by

f(x)=$\displaystyle \sum_{n=1}^{\infty} n^2x^_2n}$

as well as find its domain.

from wolframalpha i know the correct function is $\displaystyle f(x)=\frac{-x^2(x^2+1)}{(x^2-1)^3}$ although i have no idea how to prove this and it seems quite complex for a power series.

Any help is greatly appreciated.