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

Toán Lớp 9: rút gọn biểu thức B=(√2+1)(√3+1)(√6+1)(5-2√2-√3)

Toán Lớp 9: rút gọn biểu thức
B=(√2+1)(√3+1)(√6+1)(5-2√2-√3)

Comments ( 1 )

  1. #huy
    B=(\sqrt{2}+1)(\sqrt{3}+1)(\sqrt{6}+1)(5-2\sqrt{2}-\sqrt{3})
    =5\sqrt{4}-4-\sqrt{6}+5-2\sqrt{2}-\sqrt{3}
    =3\sqrt{2}+1-\sqrt{6}-sqrt{3}
    =3\sqrt{2}-\sqrt{3}-(\sqrt{6}-1)
    =\sqrt{3}(\sqrt{6}-1)-(\sqrt{6}-1)
    =(\sqrt{6}-1)(\sqrt{3}-1)
    Do đó B=(sqrt{2}+1)(5-2\sqrt{2}-\sqrt{3})(\sqrt{3}+1)(\sqrt{6}+1)
    =(\sqrt{6}-1)(\sqrt{3}-1)(\sqrt{3}+1)(\sqrt{6}+1)
    =(\sqrt{6}-1)(3-1)(\sqrt{6}-1)
    =2(\sqrt{6}-1))(\sqrt{6}+1)
    =2(6-1)
    =10

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