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222-9+11+12:2*14+14 = ? ( )

Toán Lớp 9: Ai giúp tui giải 2 bài này với nhớ ghi công thức rõ ràng nha: a) $\sqrt{4+2\sqrt{3}}$ – $\sqrt{4-2\sqrt{3}}$ b) $\sqrt{11+6\sqrt{2}}$

Toán Lớp 9: Ai giúp tui giải 2 bài này với nhớ ghi công thức rõ ràng nha:
a) $\sqrt{4+2\sqrt{3}}$ – $\sqrt{4-2\sqrt{3}}$
b) $\sqrt{11+6\sqrt{2}}$ – $\sqrt{28-10\sqrt{3}}$

Comments ( 1 )

  1. a)
    \sqrt{4+2\sqrt{3}} – \sqrt{4-2\sqrt{3}}
    =\sqrt{3+2\sqrt{3}+1} – \sqrt{3-2\sqrt{3}+1}
    =\sqrt{(\sqrt{3})²+2\sqrt{3}+1²} – \sqrt{(\sqrt{3})²-2\sqrt{3}+1²}
    =\sqrt{(\sqrt{3}+1)²} – \sqrt{(\sqrt{3}-1)²}
    =|\sqrt{3}+1|-|\sqrt{3}-1|
    =\sqrt{3}+1-\sqrt{3}+1
    =2
    b)
    \sqrt{11+6\sqrt{2}} – \sqrt{28-10\sqrt{3}}
    =\sqrt{2+2.3.\sqrt{2}+9} – \sqrt{3-2.5\sqrt{3}+25}
    =\sqrt{(\sqrt{2})²+2.3.\sqrt{3}+3²} – \sqrt{(\sqrt{3})²-2.5.\sqrt{3}+5²}
    =\sqrt{(\sqrt{2}+3)²} – \sqrt{(\sqrt{3}-5)²}
    =|\sqrt{2}+3|-|\sqrt{3}-5|
    =\sqrt{2}+3+\sqrt{3}-5
    =\sqrt{2}+\sqrt{3}-2

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222-9+11+12:2*14+14 = ? ( )

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