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

Toán Lớp 6: Chứng tỏ A chia hết cho 6 với A = 2 + 22 + 23 + 24 + … + 2100

Toán Lớp 6: Chứng tỏ A chia hết cho 6 với A = 2 + 22 + 23 + 24 + … + 2100

Comments ( 2 )

  1. A = 2 + 2^2 + 2^3 + 2^4 + … + 2^100
    = (2 + 2^2) + (2^3 + 2^4) + … + (2^99 + 2^100)
    = 6 + 2^2(2 + 2^2) + … + 2^98(2+2^2)
    = 6 + 2^2 .6 + … + 2^98 . 6
    = 6 . ( 1 + 2^2 + … + 2^98) chia hết cho 6
    => A chia hết cho 6.

  2. \(A=2+2^2+2^3+…+2^{100}\)
    \(=\left(2+2^2\right)+2^2\left(2+2^2\right)+…+2^{98}\left(2+2^2\right)\)
    \(=6+6.2^2+…+6.2^{98}\)
    \(=6\left(1+2^2+…+2^{98}\right)⋮6\)
    $#A$
    $#Xin hay nhất$
     

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

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