Math Help - Series Converges

1. Series Converges

$f(x) = \sum_{n=0}^{\infty}(-1)n\frac{x2n}{(2n)!}$

Let f be defined by the series for all x where the series converges
A. What is the domain
B. Is f odd, even or neither
C. Assuming that derivatives can be computed term by term show that f'' = f

2. Re: Series Converges

A. Use ratio test.
B. What about the function $x\mapsto x^{2n}$?
C. What have you done?

3. Re: Series Converges

You in Leache's class?

hahah

Anyway, for A domain should be infinity.
I haven't found an answer for B (could be neither)
and for C http://www.math.sunysb.edu/~disconzi...ging_index.pdf

4. Re: Series Converges

AHHH HAHA
THANKS This problem is killing me....