Đáp án:
$\begin{array}{l}
A = \dfrac{{x + y}}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}} - \dfrac{2}{{\sqrt {xy} }}:\left( {\dfrac{1}{{\sqrt x }} - \dfrac{1}{{\sqrt y }}} \right)\\
= \dfrac{{x + y}}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}} - \dfrac{2}{{\sqrt {xy} }}:\dfrac{{\sqrt y - \sqrt x }}{{\sqrt {xy} }}\\
= \dfrac{{x + y}}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}} + \dfrac{2}{{\sqrt {xy} }}.\dfrac{{\sqrt {xy} }}{{\sqrt x - \sqrt y }}\\
= \dfrac{{x + y}}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}} + \dfrac{2}{{\sqrt x - \sqrt y }}\\
= \dfrac{{x + y}}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}} + \dfrac{{2\left( {\sqrt x - \sqrt y } \right)}}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}}\\
= \dfrac{{x + y + 2\sqrt x - 2\sqrt y }}{{{{\left( {\sqrt x - \sqrt y } \right)}^2}}}
\end{array}$
