Answer
$\dfrac{1}{x^{12}}$
Work Step by Step
Using the laws of exponents, the given expression, $
\left( \dfrac{x^6}{x^2} \right)^{-3}
,$ simplifies to
\begin{array}{l}\require{cancel}
\left( x^{6-2} \right)^{-3}
\\\\=
\left( x^{4} \right)^{-3}
\\\\=
x^{4(-3)}
\\\\=
x^{-12}
\\\\=
\dfrac{1}{x^{12}}
.\end{array}