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

Toán Lớp 6: 1/.5¹+5²+5³+5⁴+…5⁵⁰ chia hết cho 6 2/.chứng tỏ:1+3¹+3²+3³+3⁴+…+3⁹⁸+3⁹⁹ chia hết cho 10 3/.chứng tỏ:2¹+2²+23+2⁴+…+2⁹⁹+2¹⁰⁰ chia hế

Tháng Ba 2, 2022 Toán học 1 Comment 0 views

Toán Lớp 6: 1/.5¹+5²+5³+5⁴+…5⁵⁰ chia hết cho 6
2/.chứng tỏ:1+3¹+3²+3³+3⁴+…+3⁹⁸+3⁹⁹ chia hết cho 10
3/.chứng tỏ:2¹+2²+23+2⁴+…+2⁹⁹+2¹⁰⁰ chia hết cho 3
Giúp em vs ạ, gấp ạ

Comments ( 1 )

  1. haianhtu97
    haianhtu97
    2 Tháng Ba, 2022 at 2:10 sáng
    Reply
    1) A = 5^1 + 5^2 + 5^3 + 5^4 + … + 5^50
    A = ( 5^1 + 5^2 ) + ( 5^3 + 5^4 ) + … + ( 5^49 + 5^50 )
    A= 1( 5^1 + 5^2 ) + 5^2( 5^1 + 5^2 ) + … + 5^48( 5^1 + 5^2 )
    A = 1 * 30 + 5^2 * 30 + … + 5^48 * 30
    A = ( 1 + 5^2 + … + 5^48 ) * 30
    ⇒ A vdots 6
    2) B = 1 + 3^1 + 3^2 + 3^3 + … + 3^98 + 3^99
    B = ( 1 + 3^1 + 3^2 + 3^3 ) + … + ( 3^96 + 3^97 + 3^98 + 3^99 )
    B = 1( 1 + 3^1 + 3^2 + 3^3 ) + … + 3^96( 1 + 3^1 + 3^2 + 3^3 )
    B = 1 * 40 + … + 3^96 * 40
    B = ( 1 + … + 3^96 ) * 40
    ⇒ B vdots 10
    3) C = 2^1 + 2^2 + 2^3 + 2^4 + … + 2^99 + 2^100
    C = ( 2^1 + 2^2 ) + ( 2^3 + 2^4 ) + … + ( 2^99 + 2^100 )
    C = 1( 2^1 + 2^2 ) + 2^2( 2^1 + 2^2 ) + … + 2^98( 2^1 + 2^2 )
    C = 1 * 6 + 2^2 * 6 + … + 2^98 * 6
    C = ( 1 + 2^2 + … + 2^98 ) * 6
    ⇒ C vdots 3

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

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