Determine the value of f(-1) when
f(x) = (x/2^2) + ((2x^3)/2^4)+((3x^5)/2^6)+... .
(Hint: differentiate the power series representation of ((x^2)-2^2)^(-1).)
The Attempt at a Solution
I was not very sure were to begin on this one. So I followed what the hint said.
the power series representation is n = 0 to infinity -sigma x^(2n)/4^(n+1)
Then i tried taking the derivative but it left me with no idea were to continue...frustrated to say the least