`\frac{a\sqrt{b}+b\sqrt{a}}{\sqrt{ab}} = \frac{\sqrt{ab}(\sqrt{a}+\sqrt{b})}{sqrt{ab}}=\sqrt{a}+\sqrt{b}` `(đk:a,b ≥0)`
`\frac{a+\sqrt{a}}{\sqrt{a}+1}=\frac{\sqrt{a}(\sqrt{a}+1)}{\sqrt{a}+1}=\sqrt{a}` `(đk:a≥0)`
`\frac{a-\sqrt{a}}{\sqrt{a}-1}=\frac{\sqrt{a}(\sqrt{a}-1)}{\sqrt{a}-1}=\sqrt{a}` `(đk:a≥0; a \ne 1)`