Chapter 9 - Roots and Radicals - Chapter 9 Test - Page 431: 13

$\dfrac{\sqrt{15xy}}{5y}$

Using the properties of radicals, the given expression, $ \dfrac{\sqrt{3x}}{\sqrt{5y}} ,$ simplifies to \begin{array}{l}\require{cancel} \dfrac{\sqrt{3x}}{\sqrt{5y}}\cdot\dfrac{\sqrt{5y}}{\sqrt{5y}} \\\\= \dfrac{\sqrt{15xy}}{(\sqrt{5y})^2} \\\\= \dfrac{\sqrt{15xy}}{5y} .\end{array}