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

Toán Lớp 6: chứng minh 4+4^2+4^3+…+4^120 chia hết cho 105

Toán Lớp 6: chứng minh 4+4^2+4^3+…+4^120 chia hết cho 105

Comments ( 1 )

  1. Lời giải chi tiết:
    4+4^2+4^3+…+4^120
    =(4+4^2+4^3+4^4+4^5+4^6)+…+(4^115+4^116+4^117+4^118+4^119+4^120)
    =4.(1+4+4^2+4^3+4^4+4^5)+…+4^115(1+4+4^2+4^3+4^4+4^5)
    =4.1365+…+4^(115).1365
    =1365.(4+…+4^115)
    =105.13.(4+…+4^115)\vdots105
    Vậy 4+4^2+4^3+…+4^120\vdots105

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