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

Toán Lớp 6: chứng minh 2+2²+2³+2⁴+2⁵+2⁶+2⁷+2⁸ chia hết cho 3

Toán Lớp 6: chứng minh 2+2²+2³+2⁴+2⁵+2⁶+2⁷+2⁸ chia hết cho 3

Comments ( 2 )

  1. 2+2^2+2^3+2^4+2^5+2^6+2^7+2^8
    =(2+2^2)+(2^3+2^4)+(2^5+2^6)+(2^7+2^8)
    =2.(1+2)+2^3.(1+2)+2^5.(1+2)+2^7.(1+2)
    =2.3 +2^3 . 3 + 2^5 . 3 + 2^7 . 3
    =3.(2+2^3+2^5+2^7) vdots 3
    Vậy 2+2^2+2^3+2^4+2^5+2^6+2^7+2^8 vdots 3

  2. Giải đáp:
    = (2+2²)+(2³+2⁴)+(2⁵+2⁶)+(2⁷+2⁸)
    = 3.2+3.2³+3.2⁵+3.2⁷
    = 3.(2+2³+2⁵+2⁷)
    => Dãy số đó chia hết cho 3
     

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

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