# Thread: power series- radius and interval of convergence

1. ## power series- radius and interval of convergence

The sum from 2 to infinite of [x^(2n)]/[n*(ln n)^2]
I tried the ratio test but it got me to some nasty thing i dont know how to solve.
thanks for any help in advance!

2. Originally Posted by Jasonium
The sum from 2 to infinite of [x^(2n)]/[n*(ln n)^2]
I tried the ratio test but it got me to some nasty thing i dont know how to solve.
Use the root test. $\sqrt[n]{{\left| {a_n } \right|}} = \frac{{x^2 }}
{{\sqrt[n]{{n\left( {\ln (n)} \right)^2 }}}}$