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

Toán Lớp 6: chứng tỏ tổng sau chia hết cho 7 S=2^1 + 2^2 + 2^3 + 2^4 + 2^5 + 2^6… 2^29

Toán Lớp 6: chứng tỏ tổng sau chia hết cho 7
S=2^1 + 2^2 + 2^3 + 2^4 + 2^5 + 2^6… 2^29

Comments ( 2 )

  1. \text{Lời giải và giải thích chi tiết}
    $\text{S=$2^{1}$ +$2^{2}$ +$2^{3}$ +…+$2^{29}$ }$
    $\text{S=($2^{1}$+$2^{2}$+$2^{3}$)+…+($2^{27}$+$2^{28}$+$2^{29}$)}$
    $\text{S=2(1+2+$2^{2}$ )+$2^{4}$ (1+2+$2^{2}$ )+…+$2^{27}$ (1+2+$2^{2}$ )}$
    $\text{S=2.7+$2^{4}$.7+…+$2^{27}$.7}$
    $\text{S=7(2+$2^{4}$+…+$2^{27}$)}$
    $\text{Vì 7$\vdots$7}$
    $\text{⇒S$\vdots$7}$

  2. S=2^1 + 2^2 + 2^3 + 2^4 + 2^5 + 2^6………………..2^29
    S=(2^1+2^2+2^3)+(2^4+2^5+2^6)+…………………+(2^27+2^28+2^29)
    S=2.(1+2+2^2)+2^4.(1+2+2^2)+…………………..+2^27.(1+2+2^2)
    S=2.7+2^4. 7+…………………….+2^27. 7
    S=7.(2+2^4+………………….+2^27)
    Vì 7vdots7
    =>Svdots7

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

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