$\"\"$

The power series is $\"\"$ .

Let $\"\"$ .

Find $\"\"$ .

$\"\"$

$\"\"$ $\"\"$ .

$\"\"$

The series is converges if and only if the value $\"\"$ .

$\"\"$

The series is converges in the interval $\"\"$ . \ \

Therefore, the series is converges in the interval $\"\"$ . \ \

$\"\"$ \ \

Interval of convergence is $\"\"$ .