Question

Mn giúp tui với 

 

A.\(\sqrt{(3+\sqrt{2)}^2}+\sqrt{6-4\sqrt{2}}\)

B.\(\sqrt{3+2\sqrt{2}}-\sqrt{6-4\sqrt{2}}\)

C.\((\sqrt{14+\sqrt{6}}).\sqrt{5-\sqrt{21}}\)

Answer 1

`a)\sqrt{(3+\sqrt{2})^2}+\sqrt{6-4\sqrt{2}}`

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

`=3+\sqrt{2}+2-\sqrt{2}=5`

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`b)\sqrt{3+2\sqrt{2}}-\sqrt{6-4\sqrt{2}}`

`=\sqrt{(\sqr{2}+1)^2}-\sqrt{(2-\sqrt{2})^2}`

`=\sqrt{2}+1-2+\sqrt{2}=2\sqrt{2}-1`

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`c)\sqrt{14+\sqrt{6}}.\sqrt{5-\sqrt{21}}`

`=\sqrt{(14+\sqrt{6})(5-\sqrt{21})}`

`=\sqrt{70-14\sqrt{21}+5\sqrt{6}-3\sqrt{14}}`

 

`->` Mk ms nghĩ đến đây thôi