The function is
.


.
Apply partial fraction decomposition.
\
.
Equate
coefficients.

.
Equate constant terms.
\
Substitute
.

Substitute
in
.

.
Substitute
and
in
.
.
Find the power series for
.
Apply the power series formula:
.
.
The power series representation of
.
.
The series is in the form of geometric series.
\The series is converges when
.
The power series representation of
.

.

Find the interval of convergence using ratio test.
\Consider
and
.

The series is converges when
.
.
The interval of convergence of
is
.
.
The interval of convergence is
.