Use the Ratio Test $to$ determine the radius $of$ convergence $of$

${\displaystyle \underset{n=1}{\overset{}{}}}\frac{x^n}{\sqrt[4]{n}*6^n}$ for

infinity, $U$ for combining intervals, and $an$ appropriate type $of$ parenthesis $"(",")","["or"]"$ depending $on$ whether the interval

$is$ open $or$ closed. Enter DNE $if$ interval $is$ empty.