Answer
$64x^{3}$
Work Step by Step
Using $(x^ay^b)^c=x^{ac}y^{bc}$ or the products-to-powers rule, the given expression, $
(4x)^3
,$ simplifies to
\begin{array}{l}\require{cancel}
4^{1(3)}x^{1(3)}
\\\\=
4^{3}x^{3}
\\\\=
64x^{3}
.\end{array}