$$\left. \begin{array} { l } { \sqrt { 25 a ^ { 6 } b ^ { 10 } } , a \gt 0 , b \lt 0 } \end{array} \right.$$
$c=-5a^{3}b^{5}$
$b=-\frac{5^{\frac{4}{5}}\sqrt[5]{c}}{5a^{\frac{3}{5}}}$
$c>0\text{ and }a>0$
