Solution of Problem 5 - Limit Comparison Test

Using the , we compare our original series åan to the series
å
bn = ¥
å
n = 2 
1
3n-1
Since

lim
n® ¥ 
an
bn
=
lim
n® ¥ 
3n-1
3n-1-1
= 1  is  finite  and  positive,
and since the series åbn is a convergent () series, we conclude that our series converges.

Furthermore, since our series has only positive terms, its convergence is .

Note that this problem could also be solved using