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

Toán Lớp 6: Cho s=2^1+2^2+2^3+-.+2^100chung mính ko chia het cho 7

Toán Lớp 6: Cho s=2^1+2^2+2^3+…..+2^100chung mính ko chia het cho 7

Comments ( 2 )

  1. S=2^1+2^2+2^3+…..+2^(100)
    ⇔S=2+2^2(1+2+2^2)+2^5(1+2+2^2)+2^(98)(1+2+2^2)
    ⇔S=2+7.2^2+7.2^5+…+7.2^(98)
    ⇔S=2+7(2^2+2^5+…+2^(98))ko chia hết cho 7

  2. Lời giải và giải thích chi tiết:
    S = 2^1 + 2^2 + 2^3 + ………… + 2^100
    S = 2^1 + (2^2 + 2^3 + 2^4) + ………….. + (2^98 + 2^99 + 2^100)
    S = 2 + 2^2(1 + 2 + 2^2) + …………. + 2^98(1 + 2 + 2^2)
    $S = 2 + 7(2^2 + ………… + 2^98) \not\vdots 7$

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

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