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

Toán Lớp 6: cho m = 2 + 2 mũ 2 + 2 mũ 3 +…+ 2 mũ 20 . CTR M chia hết cho 6

Toán Lớp 6: cho m = 2 + 2 mũ 2 + 2 mũ 3 +…+ 2 mũ 20 . CTR M chia hết cho 6

Comments ( 2 )

  1. M = 2 + 2^2 + 2^3 + …. + 2^20
    M = ( 2 + 2^2 ) + ( 2^3 + 2^4 ) + …. + ( 2^19 + 2^20 )
    M = 1 . ( 2 + 2^2 ) + 2^2 . ( 2 + 2^2 ) + …. + 2^18 . ( 2 + 2^2 )
    M = ( 2 + 2^2 ) . ( 1 + 2^2 + …. + 2^18 )
    M = 6 . ( 1 + 2^2 + …. + 2^18 ) vdots 6 ( Điều phải chứng minh )

  2. Giải đáp:
    Giải
    $A$ = ( $2$ + $2^{2}$ ) + ( $2^{3}$ + $2^{4}$ ) +…+ ( $2^{17}$ + $2^{18}$ ) + ( $2^{19}$ + $2^{20}$ )  
    $A$ = $6$ + $2^{3}$ × ( $2$ + $2^{2}$ ) + … + $2^{17}$ × ( $2$ + $2^{2}$ ) + $2^{19}$ × ( $2$ + $2^{2}$ )
    $A$ = $6$ + $2^{3}$ × 6 +…+ $2^{17}$ × 6 + $2^{19}$ × 6
    $A$ = $6$ × ( $1$ + $2^{3}$ +….+ $2^{17}$ + $2^{19}$ )
    $\Rightarrow$ $A$ $\vdots$ $6$

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