Answer
$2x\sqrt[4]{3x}$
Work Step by Step
Factor the radicand (expression inside the radical sign) so that some factors are perfect roots (4th power) to obtain:
$$=\sqrt[4]{(16x^4)(3x)}\\
=\sqrt[4]{(2x)^4(3x)}$$
Use the Product Rule $\sqrt[n]{ab}=\sqrt[n]{a}\cdot \sqrt[n]{b}\quad$ and $\quad \sqrt[n]{a^n}=n, a\ge0$, to obtain
$$
=\sqrt[4]{(2x)^4} \cdot \sqrt[4]{3x}\\
=2x\sqrt[4]{3x}
$$
