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

Toán Lớp 6: 13×2^x+2-5×2^x+1+7×2^x=98 nhanh vs ak

Toán Lớp 6: 13×2^x+2-5×2^x+1+7×2^x=98 nhanh vs ak

Comments ( 2 )

  1. #tnvt
    13.2^(x+2)-5.2^(x+1)+7.2^x=98
    =>13.2^x .2^2-5.2^x .2^1+7.2^x=98
    =>2^x .(13.4-5.2+7)=98
    =>2^x .49=98
    =>2^x=2
    =>2^x=2^1
    =>x=1
    Vậy x=1
     

  2. 13 . 2^{x+2} – 5 . 2^{x+1} + 7 .2^{x} = 98
    2^{x} . (13 . 4 – 5 . 2 + 7) = 98
    2^{x} . (52 – 10 + 7) = 98
    2^{x} . (42 + 7) = 98
    2^{x} . 49 = 98
    2^{x} = 98 : 49
    2^{x} = 2
    2^{x} = 2^{1}
    x = 1

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

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