Question

Answer 1

Bài 57:

a: \(=\left(\dfrac{\sqrt{x}}{\sqrt{y}\left(\sqrt{x}-\sqrt{y}\right)}-\dfrac{2\sqrt{x}-\sqrt{y}}{\sqrt{x}\left(\sqrt{x}-\sqrt{y}\right)}\right)\cdot\dfrac{\sqrt{xy}}{\sqrt{x}-\sqrt{y}}\)

\(=\dfrac{x-2\sqrt{xy}+y}{\sqrt{xy}\left(\sqrt{x}-\sqrt{y}\right)}\cdot\dfrac{\sqrt{xy}}{\sqrt{x}-\sqrt{y}}\)

\(=\dfrac{\left(\sqrt{x}-\sqrt{y}\right)^2}{\left(\sqrt{x}-\sqrt{y}\right)^2}=1\)

b: \(=\dfrac{\left(x-2\sqrt{xy}+y\right)}{x-y}+\dfrac{2\sqrt{y}}{\sqrt{x}+\sqrt{y}}\)

\(=\dfrac{\sqrt{x}-\sqrt{y}+2\sqrt{y}}{\sqrt{x}+\sqrt{y}}=1\)