Đáp án + Giải thích các bước giải:
`a)P=\sqrt{11+6\sqrt{2}}-\sqrt{11-6\sqrt{2}}`
`=\sqrt{9+2.3.\sqrt{2}+2}-\sqrt{9-2.3.\sqrt{2}+2}`
`=\sqrt{(9+\sqrt{2})^2}-\sqrt{(9-\sqrt{2})^2}`
`=|9+\sqrt{2}|-|9-\sqrt{2}|`
`=9+\sqrt{2}-9+\sqrt{2}=2\sqrt{2}`
`b)Q=\sqrt{17+12\sqrt{2}}-\sqrt{17-12\sqrt{2}}`
`=\sqrt{9+2.3.2\sqrt{2}+(2\sqrt{2})^2}-\sqrt{9-2.3.2\sqrt{2}+(2\sqrt{2})^2}`
`=\sqrt{(3+2\sqrt{2})^2}-\sqrt{(3-2\sqrt{2})^2}`
`=|3+2\sqrt{2}|-|3-2\sqrt{2}|`
`=3+2\sqrt{2}-3+2\sqrt{2}=4\sqrt{2}`
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