Đáp án :
`1)` `\sqrt2`
`2)` `\frac{1}{\sqrt2}`
`3)` `\frac{\sqrt3}{\sqrt2}`
Giải thích các bước giải :
`1)` `\frac{2 + \sqrt2}{1 + \sqrt2 }`
`= \frac{ \sqrt2 ( \sqrt2 + 1 )}{1 + \sqrt2}`
`= \sqrt2`
`2)` `\frac{\sqrt2 - 1}{2 - \sqrt2}`
`= \frac{\sqrt2 - 1}{\sqrt2 (\sqrt2 -1)}`
`= \frac{1}{\sqrt2}`
`3)` `\frac{2 . \sqrt3 - \sqrt6}{\sqrt8 - 2}`
`= \frac{2 . \sqrt3 - \sqrt2 . \sqrt3}{2\sqrt2 - 2}`
`= \frac{\sqrt3 ( 2 - \sqrt2 )}{\sqrt2 (2 - \sqrt2)}`
`= \frac{\sqrt3}{\sqrt2}`