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

Toán Lớp 6: cho s=3+3^2+3^3+3^4+=+3^59+3^60 chứng minh rằng s chia hết cho 10

Toán Lớp 6: cho s=3+3^2+3^3+3^4+…………+3^59+3^60 chứng minh rằng s chia hết cho 10

Comments ( 2 )

  1. Answer
    S = 3 + 3^{2} + 3^{3} + 3^{4} + … + 3^{57} + 3^{58} + 3^{59} + 3^{60}
    S = (3 + 3^{2} + 3^{3} + 3^{4}) + … + (3^{57} + 3^{58} + 3^{59} + 3^{60})
    S = 3 . (1 + 3 + 3^{2} + 3^{3}) + … + 3^{57} . (1 + 3 + 3^{2} + 3^{3})
    S = 3 . 40 + … + 3^{57} . 40
    S = 40 . (3 + … + 3^{57})
    S = 4 . 10 . (3 + … + 3^{57}) \vdots 10
    $\text{Vậy bài toán được chứng minh}$

  2. S=3+3^2+3^3+3^4+…+3^59+3^60
    =(3+3^2+3^3+3^4)+…+(3^57+3^58+3^59+3^60)
    =3(1+3+3^2+3^3)+…+3^57(1+3+3^2+3^3)
    =3.40+3^4 .40+…+3^57 .40
    =40(3+3^4+…+3^57)
    Vì 40\vdots10
    =>40(3+3^4+…+3^57)\vdots10
    Vậy S\vdots10
     

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

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