Answer
$\dfrac{1}{y^{6}b^{4}x^{4}}$
Work Step by Step
Using laws of exponents, the given expression simplifies to
\begin{align*}
&
y^2\left( y^2bx \right)^{-4}
\\\\&=
y^2\left( y^{2(-4)}b^{-4}x^{-4} \right)
\\\\&=
y^2\left( y^{-8}b^{-4}x^{-4} \right)
\\\\&=
y^{2+(-8)}b^{-4}x^{-4}
\\\\&=
y^{-6}b^{-4}x^{-4}
\\\\&=
\dfrac{1}{y^{6}b^{4}x^{4}}
.\end{align*}
