Answer
4x
Work Step by Step
$\sqrt[3] (8x)\times\sqrt[3] (8x^{2})=\sqrt[3] (8x\times8x^{2})=\sqrt[3] (64x^{3})=\sqrt[3] (64\times x^{3})=\sqrt[3] 64\times\sqrt[3] (x^{3})=4x$
We know that $\sqrt[3] 64=4$, because $4^{3}=64$.
We know that $\sqrt[3] (x^{3})=x$, because $(x)^{3}=x^{3}$.