Answer
$6$
Work Step by Step
Using $\sqrt[n]{\dfrac{x}{y}}=\dfrac{\sqrt[n]{x}}{\sqrt[n]{y}},$ the given expression is equivalent to:
\begin{align*}
&
=\sqrt[]{\dfrac{216}{6}}
\\\\&=
\sqrt[]{36}
\\\\&=
\sqrt[]{6^2}
\\\\&=
6
\end{align*}
Hence, the simplified form of the given expression is $
6
$.
