Factor $125=5^{2}\times 5$. Rewrite the square root of the product $\sqrt{5^{2}\times 5}$ as the product of square roots $\sqrt{5^{2}}\sqrt{5}$. Take the square root of $5^{2}$.
$$\frac{-13\times 5\sqrt{5}}{5}\sqrt{65}$$
Multiply $-13$ and $5$ to get $-65$.
$$\frac{-65\sqrt{5}}{5}\sqrt{65}$$
Divide $-65\sqrt{5}$ by $5$ to get $-13\sqrt{5}$.
$$-13\sqrt{5}\sqrt{65}$$
Factor $65=5\times 13$. Rewrite the square root of the product $\sqrt{5\times 13}$ as the product of square roots $\sqrt{5}\sqrt{13}$.
