Answer
$-7\sqrt[3]{n^2}$.
Work Step by Step
The given expression is
$=-\sqrt[3]{343n^2}$
Factor as cube terms.
$=-\sqrt[3]{343\cdot n^2}$
Use product property of cube roots.
$=-\sqrt[3]{343}\cdot \sqrt[3]{n^2}$
Use $343=7^3$.
$=-\sqrt[3]{7^3}\cdot \sqrt[3]{n^2}$
Simplify.
$=-7\sqrt[3]{n^2}$.
