Answer
$\frac{y^{5}}{3x^{3}}$
Work Step by Step
$\sqrt (\frac{y^{10}}{9x^{6}})=\frac{y^{5}}{3x^{3}}$, because $(\frac{y^{5}}{3x^{3}})^{2}=\frac{y^{5}}{3x^{3}}\times\frac{y^{5}}{3x^{3}}=\frac{y^{5+5}}{(3\times3)\times x^{3+3}}=\frac{y^{10}}{9x^{6}}$
