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

Toán Lớp 6: cho T=2+`2^2`+`2^3`+`2^4`+`2^5`+`2^6`+…+`2^2015`+`2^2016`.chứng tỏ T chia hết cho 14

Toán Lớp 6: cho T=2+2^2+2^3+2^4+2^5+2^6+…+2^2015+2^2016.chứng tỏ T chia hết cho 14

Comments ( 2 )

  1. T=2+2^2 +2^3+2^4+2^5+2^6+…+2^{2015}+2^{2016}
    =(2+2^2+2^3)+(2^4+2^5+2^6)+….+(2^{2014}+2^2015 +2^2016)
    =2.(1+2+2^2)+2^4.(1+2+2^2)+….+2^{2014}..(1+2+2^2)
    =2.7+2^4 .7 +…..+2^2014 .7
    =7.(2+2^4 +….+2^2014}
    =>T \vdots 7
    Ta lại có :
    T=2+2^2 +2^3+2^4+2^5+2^6+…+2^{2015}+2^{2016}
    =2xx1+2xx2+2xx2^2 +2xx2^3 +…..+2xx2^2014 +2xx2^2015
    =2xx(1+2+2^2 +2^3 +…+2^2014 +2^2015)
    =>T \vdots 2
    Vì T \vdots 2 và \vdots 7
    =>T \vdots 14
     

  2. Lời giải chi tiết:
    T=2+2^2+2^3+2^4+2^5+2^6+…+2^2015+2^2016
    T=(2+2^2+2^3)+(2^4+2^5+2^6)+…+(2^2014+2^2015+2^2016)
    T=1.(2+2^2+2^3)+2^3.(2+2^2+2^3)+…+2^2013.(2+2^2+2^3)
    T=1.14+2^(3).14+…+2^(2013).14
    T=14.(1+2^3+…+2^2013)\vdots14
    Vậy T\vdots14

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

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