Alternating Series Test :
\If the alternating series satisfies
(i) ,
(ii) , then the series is convergent.
The series is .
Since the series is alternating, verify condition (i) and (ii) of the Alternating Series Test.
\It is not obvious that the sequence given by is decreasing.
Consider the related function .
Differentiate the function with respect to x .
\If the function is decreasing, then .
\
Thus, is decreasing on the interval
.
This means that, and therefore,
, when
.
The inequality can be verified directly but all that really matters is that the sequence
is eventually decreasing.
Thus, condition (i) is verified.
\Find .
As , then
.
Evaluate the limits.
\.
Thus, condition (ii) is verified.
\Thus the given series is convergent by the Alternating Series Test.
\The series is convergent.