Evaluate:

$\sqrt[3]{\frac{-512}{343}}$

By factorisation:

                         

$\sqrt[3]{\frac{512}{343}}=\frac{\sqrt[3]{8 \times 8 \times 8}}{\sqrt[3]{7 \times 7 \times 7}}$

$\sqrt[3]{\frac{-512}{343}}=\frac{-8}{7}$