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

Toán Lớp 9: B= 15/√6+1 + 4/√6-2 – 12/3-√6 -√6 help

Toán Lớp 9: B= 15/√6+1 + 4/√6-2 – 12/3-√6 -√6 help

Comments ( 2 )

  1. Giải đáp:
    B=-11 
    Lời giải và giải thích chi tiết:
    B= {15}/{\sqrt{6}+1} + 4/{\sqrt{6}-2} – {12}/{3-\sqrt{6}}-\sqrt{6}
    ={15(\sqrt{6}-1)}/{(\sqrt{6}+1)(\sqrt{6}-1)}+{4(\sqrt{6}+2)}/{(\sqrt{6}-2)(\sqrt{6}+2)}-{12(3+\sqrt{6})}/{(3-\sqrt{6})(3+\sqrt{6})}-\sqrt{6}
    ={3.5(\sqrt{6}-1)}/{6-1^2}+{2.2(\sqrt{6}+2)}/{6-2^2}-{3.4(3+\sqrt{6})}/{3^2-6}-\sqrt{6}
    =3(\sqrt{6}-1)+2(\sqrt{6}+2)-4(3+\sqrt{6})-\sqrt{6}
    =3\sqrt{6}-3+2\sqrt{6}+4-12-4\sqrt{6}-\sqrt{6}
    =(3+2-4-1).\sqrt{6}-3+4-12=-11
    Vậy B=-11

  2. Giải đáp:
     \(B=-11\)
    Lời giải và giải thích chi tiết:
     \(B=\dfrac{15}{\sqrt{6}+1} +\dfrac{4}{\sqrt{6}-2}-\dfrac{12}{3-\sqrt{6}}\\B = \dfrac{15(\sqrt{6}-1)}{(\sqrt{6}+1)(\sqrt{6}-1)}+\dfrac{4(\sqrt{6}+2)}{(\sqrt{6}-2)(\sqrt{6}+2)}-\dfrac{12(3+\sqrt{6})}{(3-\sqrt{6})(3+\sqrt{6})}-\sqrt{6}\\B= \dfrac{15(\sqrt{6-1})}{5}+\dfrac{4(\sqrt{6}+2)}{2}+\dfrac{12(3+\sqrt{6})}{3}-\sqrt{6}\\B = 3(\sqrt{6}-1)+2(\sqrt{6}+2)-4(3+\sqrt{6})-\sqrt{6}\\B = 3\sqrt{6}-3+2\sqrt{6}+4 -12 -4\sqrt{6}-\sqrt{6}\\B=0-11\\B=-11\)

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

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