Question

help me find my mistake please

Answer 1

You are given the following series.
x2 cos(x2) = x2 − x^6/2!+ x^10/4!− x^14/6!+ ⋯Find an expression for the general term of the series if the index starts with k = 0.

Answer 2

\[\sum_{k=0}^{\infty}\frac{ (-1)^{k}x^{2(2k+1)} }{ (2k)! }\]

Answer 3

that looks good to me !