\(A=\frac{\left(\sqrt{x}+\sqrt{y}\right)^2}{\sqrt{x}\left(\sqrt{x}+\sqrt{y}\right)}.\frac{\left(\sqrt{x}-\sqrt{y}\right)^2}{\sqrt{y}\left(\sqrt{x}-\sqrt{y}\right)}=\frac{\sqrt{x}+\sqrt{y}}{\sqrt{x}}.\frac{\sqrt{x}-\sqrt{y}}{\sqrt{y}}=\frac{x-y}{\sqrt{xy}}\)