$\"\"$

The function is $\"\"$ .

Divide the numerator and denominator by 3.

$\"\"$

The power series is $\"\"$ .

$\"\"$ .

$\"\"$

The above series is a geometric series with common ratio $\"\"$ .

Geometric series is convergent when common ratio $\"\"$ .

Therefore, the series is convergent if $\"\"$

$\"\"$

Interval of convergence is $\"\"$ .

$\"\"$

Power series representation of the function is $\"\"$ and

Interval of convergence is $\"\"$ .