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

Toán Lớp 6: chứng tỏ :(1+2+2^2+2^3+2^4+2^+2^6+2^7+2^8+2^9) chia hết cho 3

Toán Lớp 6: chứng tỏ :(1+2+2^2+2^3+2^4+2^+2^6+2^7+2^8+2^9) chia hết cho 3

Comments ( 2 )

  1. 1+2+2^2+2^3+…+2^9
    =(1+2)+(2^2+2^3)+…+(2^8+2^9)
    =1.(1+2)+2^2(1+2)+…+2^8(1+2)
    =1.3+2^2 .3+…+2^8 .3
    =(1+2^2+…+2^8).3 \vdots 3
    =>1+2+2^2+2^3+…+2^9 \vdots 3(đpcm)

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