Tính giá trị biểu thức: [tex]P=\frac{y\sqrt{x}+\sqrt{x}+x\sqrt{y}+\sqrt{y}}{\sqrt{xy}+1}[/tex] (x, y > 0).
$P=\frac{y\sqrt{x}+\sqrt{x}+x\sqrt{y}+\sqrt{y}}{\sqrt{xy}+1}=\frac{(y\sqrt{x}+x\sqrt{y})+(\sqrt{x}+\sqrt{y})}{\sqrt{xy}+1}=\frac{\sqrt{xy}(\sqrt{x}+\sqrt{y})+(\sqrt{x}+\sqrt{y})}{\sqrt{xy}+1} = \frac{(\sqrt{x}+\sqrt{y})(\sqrt{xy}+1)}{\sqrt{xy}+1}=\sqrt{x}+\sqrt{y}$