Answer
$\dfrac{x}{\sqrt[4]{y}}$
Work Step by Step
Using the laws of exponents, the given expression, $
xy^{-1/4}
,$ is equivalent to
\begin{array}{l}\require{cancel}
\dfrac{x}{y^{1/4}}
.\end{array}
Using $a^{m/n}=\sqrt[n]{a^m}=(\sqrt[n]{a})^m$, the expression, $
\dfrac{x}{y^{1/4}}
,$ simplifies to
\begin{array}{l}\require{cancel}
\dfrac{x}{\sqrt[4]{y^1}}
\\\\=
\dfrac{x}{\sqrt[4]{y}}
.\end{array}