Đáp án:
$\begin{array}{l}
a)\sqrt {\dfrac{2}{3}} = \dfrac{{\sqrt 6 }}{3}\\
b)\sqrt {\dfrac{5}{{12}}} = \dfrac{{\sqrt 5 }}{{2\sqrt 3 }} = \dfrac{{\sqrt {15} }}{6}\\
c)\sqrt {\dfrac{3}{x}} = \dfrac{{\sqrt {3x} }}{x}\\
d)\sqrt {\dfrac{{3x}}{{2y}}} = \dfrac{{\sqrt {6xy} }}{{2y}}
\end{array}$