Register Now

Login

Lost Password

Lost your password? Please enter your email address. You will receive a link and will create a new password via email.

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

Toán Lớp 6: Cho S=1+3+3²+3³+3⁴+3⁵+…+3²⁰²¹.Chứng minh rằng S chia hết cho 13

Toán Lớp 6: Cho S=1+3+3²+3³+3⁴+3⁵+…+3²⁰²¹.Chứng minh rằng S chia hết cho 13

Comments ( 2 )

  1. S=1+3+3^2+3^3+3^4+3^5+………………..+3^2021
    S=(1+3+3^2)+(3^3+3^4+3^5)+…………………..+(3^2019+3^2020+3^2021)
    S=1.(1+3+3^2)+3^3.(1+3+3^2)+…………………..+3^2019.(1+3+3^2)
    S=1.13+3^3. 13+………………….+3^2019. 13
    S=13.(1+3^3+……………….+3^2019)
    Vì 13vdots13
    =>Svdots13
     

  2. $@Elaina2k4$
    Giải đáp:
     =>A chia cho 13 dư 5
    Lời giải và giải thích chi tiết:
    A=1+3+3^2+3^3+…+3^2021
    =1+3+(3^2+3^3+3^4+3^5)+(3^6+3^7+3^8+3^9)+…..+(3^2018+3^2019+3^2020+3^2021)
    =4+3^2 . 40 + 3^6 . 40 + … + 3^2018 . 40
    =4+40 . (3^2 + 3^6 + … + 3^2018)
    =>A chia cho 13 dư 5

Leave a reply

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

About Khanh