căn( 5 + 2 căn 6) - căn (5-2 căn 6)

`\text{Đáp án+ Giải thích các bước giải:}`

`\sqrt{5+2\sqrt{6}}-\sqrt{5-2\sqrt{6}`

`=\sqrt{3+2\sqrt{3*2}+2}-\sqrt{3-2\sqrt{3*2}+2`

`=\sqrt{(\sqrt{3}+\sqrt{2})^2}-\sqrt{(\sqrt{3}-\sqrt{2})^2}`

`=|\sqrt{3}+\sqrt{2}|-|\sqrt{3}-\sqrt{2}|`

`=\sqrt{3}+\sqrt{2}-(\sqrt{3}-\sqrt{2})`

`=\sqrt{3}+\sqrt{2}-\sqrt{3}+\sqrt{2}`

`=2\sqrt{2}`

`\sqrt{5+2\sqrt{6}}-\sqrt{5-2\sqrt{6}}`

`=\sqrt{2+2.\sqrt{2}.\sqrt{3}+3}-\sqrt{3-2.\sqrt{3}.\sqrt{2}+2}`

`=\sqrt{(\sqrt{2}+\sqrt{3})^2}-\sqrt{(\sqrt{3}-\sqrt{2})^2}`

`=|\sqrt{2}+\sqrt{3}|-|\sqrt{3}-\sqrt{2}|`

`=\sqrt{2}+\sqrt{3}-\sqrt{3}+\sqrt{2}`

`=2\sqrt{2}`