`\qquad A=(\sqrt{a}/(\sqrt{ab}-b)+\sqrt{b}/(\sqrt{ab}-a))(a\sqrt{b}-b\sqrt{a})`
Với `a>0; b>0; a\neb` thì
`A=(\sqrt{a}/(\sqrt{b}(\sqrt{a}-\sqrt{b})) +\sqrt{b}/(-\sqrt{a}(\sqrt{a}-\sqrt{b}))) .\sqrt{ab}(\sqrt{a}-\sqrt{b})`
`A=(a-b)/(\sqrt{ab}(\sqrt{a}-\sqrt{b})). \sqrt{ab}(\sqrt{a}-\sqrt{b})`
`A=a-b`
Vậy `A=a-b` với `a>0;b>0;a\neb`