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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 giúp mik nhé

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
giúp mik nhé

Comments ( 2 )

  1. $A = 2 + 2^{2} + 2^{3} + 2^{4} + … + 2^{100}$
    $A = (2 + 2^{2}) + (2^{3} + 2^{4}) + … + (2^{99} + 2^{100})$
    $A = 6 + 2^{2} . (2 + 2^{2}) + … + 2^{98} . (2 + 2^{2})$
    $A = 6 + 2^{2} . 6 + … + 2^{98} . 6$
    $A = 6 . (1 + 2^{2} + … + 2^{98})$
    $\text{→ A chia hết cho 6.}$
    $\text{→ A chia hết cho 3.}$

  2. $\text{A = 2 + 2² + 2³ + $2^{4}$ + … + $2^{100}$ }$
      $\text{= ( 2 + 2² ) + ( 2³ + $2^{4}$ ) + …. + ( $2^{99}$ + $2^{100}$ )}$
      $\text{= ( 2 + 4 ) + 2². ( 2 + 2² ) + …. + $2^{98}$. ( 2 + 2² )}$
      $\text{= 6 + 2². 6 + … + $2^{98}$. 6 }$
        $\text{⇒ A $\vdots$ 6 mà 6 $\vdots$3}$
    $\text{⇒ A $\vdots$ 3}$
    $\text{Xin hay nhất và cám ơn ạ}$

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

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