Answer
$\dfrac{x^{2}}{16}$
Work Step by Step
Using the laws of exponents, the given expression, $
\left( 4x^{-1} \right)^{-2}
,$ simplifies to
\begin{array}{l}\require{cancel}
4^{1(-2)}x^{-1(-2)}
\\\\=
4^{-2}x^{2}
\\\\=
\dfrac{x^{2}}{4^{2}}
\\\\=
\dfrac{x^{2}}{16}
.\end{array}