Answer
$\sqrt[6]{(4a^3b)^5}$
Work Step by Step
Using the definition of rational exponents which is given by $a^{\frac{m}{n}}=\sqrt[n]{a^m}=\left(\sqrt[n]{a}\right)^m,$ the expression above is equivalent to
\begin{array}{l}\require{cancel}
(4a^3b)^{5/6}
\\\\=
\sqrt[6]{(4a^3b)^5}
.\end{array}