Answer
$\dfrac{1}{\sqrt[7]{256x^4y^4}}
$
Work Step by Step
RECALL:
(i) $a^{-\frac{m}{n}}=\dfrac{1}{a^{\frac{m}{n}}}$
(ii) $a^{\frac{m}{n}}=\sqrt[n]{a^m}$
(iii) $(ab)^m=a^mb^m$
Use the rules above to obtain:
$=\dfrac{1}{(4xy)^{\frac{4}{7}}}
\\=\dfrac{1}{\sqrt[7]{(4xy)^4}}
\\=\dfrac{1}{\sqrt[7]{4^4x^4y^4}}
\\=\dfrac{1}{\sqrt[7]{256x^4y^4}}
$
