Test the series for convergence or divergence using the Alternating Series Test.

${\displaystyle \underset{n=1}{\overset{}{}}}9(-1{)}^n{e}^{-n}$

Identify $b_n.$

$9(-1{)}^n{e}^{-n}$

Test the series for convergence or divergence using the Alternating Series Test.

$\underset{n}{lim}{b}_n$

Since $\underset{n}{lim}{b}_n\mathrm{.}0$ and $b_{n+1}{b}_n$ for all $n,$ the series converges

$$ Need Help? $$