Is this correct?

Question

determine if absolutely convergent and convergent

1. the series from n=0 to infinity of ((-1)^n)/n!

I said it was abs. conv, and therefore conv

2. the series from n=0 to infinity of
(-1)^n/(the square root of (n^2+n+1))

I said ratio test was inconclusive so not abs. conv. but conv. from the A.S.T.

3. the series from n=1 to infinity of (-1)^(n+1)/n^4

I wasn't sure how to do this one, I know not abs. conv. because the ratio test was one but how do you tell if conv?