Question

Помогите с решением ​

Answer 1

$........=\frac{\sqrt{xy}(x+\sqrt{xy})}{x+\sqrt{xy} } *\frac{x-y}{\sqrt{xy}-y } =\frac{x\sqrt{xy}+xy-xy }{x+\sqrt{xy} } *\frac{x-y}{\sqrt{xy}-y } =\frac{x\sqrt{xy}(x-y) }{(x+\sqrt{xy})(\sqrt{xy} -y)} =\\ \\ =\frac{x\sqrt{xy}(x-y)}{x\sqrt{xy}-xy+xy-y\sqrt{xy}  } =\frac{x\sqrt{xy}(x-y)}{x\sqrt{xy}-y\sqrt{xy}  } =\frac{x\sqrt{xy}(x-y)}{\sqrt{xy}(x-y) } =x$

при  х=20 будет равно 20.