We have the next expression
[tex]\sqrt[]{32a^5b^{15}}[/tex]In order to simplify we will factorize the expression in a next way
[tex]\sqrt[]{4\cdot4\cdot2\cdot a^4\cdot b^{14}\cdot b}[/tex][tex]\sqrt[]{4}\cdot\sqrt[]{4}\cdot\sqrt[]{2}\cdot\sqrt[]{a^4}\cdot\sqrt[]{b^{14}}\cdot\sqrt[]{ab}[/tex]Then we simplify the results
[tex]2\cdot2\cdot a^2\cdot b^7\cdot\sqrt[]{2ab}[/tex][tex]4a^2b^7\sqrt[]{2ab}[/tex]the simplification is
[tex]4a^2b^7\sqrt[]{2ab}[/tex]