Answer
$\dfrac{\sqrt[3]{36x^2}}{3x}$
Work Step by Step
Rationalizing the denominator of $
\sqrt[3]{\dfrac{4}{3x}}
$ results to
\begin{array}{l}\require{cancel}
\sqrt[3]{\dfrac{4}{3x}\cdot\dfrac{9x^2}{9x^2}}
\\\\=
\sqrt[3]{\dfrac{36x^2}{27x^3}}
\\\\=
\dfrac{\sqrt[3]{36x^2}}{3x}
.\end{array}