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

Toán Lớp 6: cho A = 2 + 2 mũ 2 + 2 mũ 3 + 2 mũ 4 + –. + 2 mũ 100 .chứng minh A chia hết cho 3

Toán Lớp 6: cho A = 2 + 2 mũ 2 + 2 mũ 3 + 2 mũ 4 + ……… + 2 mũ 100 .chứng minh A chia hết cho 3

Comments ( 1 )

  1. A = 2 + 2^2 + 2^3 + 2^4 + … + 2^100
    A = ( 2 + 2^2 + 2^3 + 2^4 ) + … + ( 2^97 + 2^98 + 2^99 + 2^100 )
    A = 1( 2 + 2^2 + 2^3 + 2^4 ) + … + 2^97( 2 + 2^2 + 2^3 + 2^4 )
    A = 1 * 30 + … + 2^97 * 30
    A = ( 1 + … + 2^97 ) * 30
    ⇒ A vdots 30 ( đpcm )
     

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