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

Toán Lớp 6: Anh em nào giỏi giải hộ mình :2+2^2+2^3+2^4+…+2^2017=?

Toán Lớp 6: Anh em nào giỏi giải hộ mình :2+2^2+2^3+2^4+…+2^2017=?

Comments ( 1 )

  1. Đặt:
    A = 2 + 2^2 + 2^3 + 2^4 + … + 2^2017
    2A = 2^2 + 2^3 + 2^4 + 2^5 + … + 2^2018
    2A – A = (2^2 + 2^3 + 2^4 + 2^5 + … + 2^2018) – (2 + 2^2 + 2^3 + 2^4 + … + 2^2017)
    A = 2^2018 – 2
    Vậy 2 + 2^2 + 2^3 + 2^4 + … + 2^2017 = 2^2018 – 2
     

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

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