The function is
.



.
Apply partial fraction decomposition.
\



.
Equate
coefficients.

.
Equate constant terms.
\
Substitute
.



.
Substitute
in
.

.
Substitute
and
in
.
.
Find the power series.
\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
.
.
is geometric series.
The series is converges when
.

.
Consider
.


The interval of convergence of
is
is
.
.
The interval of convergence is
.