tính tổng C= 1/3 +1/3^2+1/3^3+…+1/3^10 dấu/ là phân số nha các bạn

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tính tổng C= 1/3 +1/3^2+1/3^3+…+1/3^10 dấu/ là phân số nha các bạn

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Calantha 6 years 2020-10-25T07:41:59+00:00 2 Answers 93 views 0

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  1. Adela
    0
    2020-10-25T07:43:36+00:00
    Reply

    Giải thích các bước giải:

    `C= 1/3 +1/3^2+1/3^3+…+1/3^10 `

    `=>3C= 1 +1/3+1/3^2+…+1/3^9`

    `=>3C-C=(1 +1/3+1/3^2+…+1/3^9)-( 1/3 +1/3^2+1/3^3+…+1/3^10)`

    `=>2C=1-1/3^10=(3^10-1)/3^10`

    `=>C=(3^10-1)/2.3^10`

  2. quangkhai
    0
    2020-10-25T07:43:40+00:00
    Reply

    Đáp án:

    `C= 1/3 +1/3^2+1/3^3+…+1/3^10`

    `=> 3C = 1 + 1/3 + 1/3^2 + … + 1/3^9`

    `=> 3C – C = (1 + 1/3 + 1/3^2 + … + 1/3^9) – ( 1/3 +1/3^2+1/3^3+…+1/3^10)`

    `=> 2C = 1 + 1/3 + 1/3^2 + … + 1/3^9 – 1/3 -1/3^2-1/3^3-…-1/3^10`

    `=> 2C = 1 – 1/3^10`

    `=> C = (1 – 1/3^10)/2`

    ` Go od luck !`

     

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