[tex]\bf \sqrt[3]{-\cfrac{125}{729}}~~ \begin{cases} 125=&5\cdot 5\cdot 5\\ &5^3\\ 729=&9\cdot 9\cdot 9\\ &9^3 \end{cases}\implies \sqrt[3]{-\cfrac{5^3}{9^3}}\implies \sqrt[3]{(-1)^3\cdot \cfrac{5^3}{9^3}}\implies -\cfrac{5}{9}[/tex]
