Bài làm :
`\sqrt{11+4\sqrt{6}}`
`=\sqrt{8+2.2\sqrt{2}.\sqrt{3}+3}`
`=\sqrt{(2\sqrt{2})^2+2.2\sqrt{2}.sqrt{3}+(\sqrt{3})^2}`
`=\sqrt{(2\sqrt{2}+\sqrt{3})^2}`
`=|2\sqrt{2}+\sqrt{3}|`
`=2\sqrt{2}+\sqrt{3}`
$\\$
`\sqrt{14-6\sqrt{5}}`
`=\sqrt{9-2.3.\sqrt{5}+5}`
`=\sqrt{3^2-2.3.\sqrt{5}+(\sqrt{5})^2}`
`=\sqrt{(3-\sqrt{5})^2}`
`=|3-\sqrt{5}|`
`=3-\sqrt{5}`