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

Toán Lớp 6: a) A = 1+ 2 + 2^2 +…+2^10 b) B = 3 + 3^2 + 3^3 +…+ + 3^10 C) c = 5+ 5^3 + 5^5 +…+5^97 + 5^99

Toán Lớp 6: a) A = 1+ 2 + 2^2 +…+2^10
b) B = 3 + 3^2 + 3^3 +…+ + 3^10
C) c = 5+ 5^3 + 5^5 +…+5^97 + 5^99

Comments ( 2 )

  1. Giải đáp + Lời giải và giải thích chi tiết:
    a) A = 1 + 2 + 2^2 + … + 2^10
    = > 2 . A =  2 + 2^2 + 2^11
    = > 2 . A – A = ( 2 + 2^2 + 2^11) – (1 + 2 + 2^2 + … + 2^10)
                A = 2^11 – 1
    b) B = 3 + 3^2 + … + 3^10
    = > 3 . B = 3^2 + 3^3 + … + 3^11
    = > 3 . B – B = (3^2 + 3^3 + … + 3^11) – (3 + 3^2 + … + 3^10)
                 2 . B = 3^11 – 3
    = > B = {3^11 – 3}/2
    c) C = 5 + 5^3 + 5^5 + … + 5^99
    = > 25 . C = 5^3 + 5^5 + … + 5^101
    = > 25 . C – C = (5^3 + 5^5 + … + 5^101) – (5 + 5^3 + 5^5 + … + 5^99)
              24 . C = 5^101 – 5
    = > C = {5^101 – 5}/24
    Xin 5 sao và hay nhất

  2. A=1+2+2^2+…+2^10
    2A=2+2^3+2^3+2^4+…+2^11
    2A-A=(2+2^3+2^3+2^4+…+2^11)-(1+2+2^2+…+2^10)
    A=2^11 -1
    ———-
    B=3+3^2+3^3+…+3^10
    3B=3^2+3^3+3^4+…+3^11
    3B-B=(3^2+3^3+3^4+…+3^11)-(3+3^2+3^3+…+3^10)
    2B=3^11 -3
    B=(3^11 -3)/2
    —————-
    C=5+5^3+5^5+..+5^97+5^99
    5^2 C=5^3+5^5+5^7+…+5^99+5^101
    25C-C=(5^3+5^5+5^7+…+5^99+5^101)-(5+5^3+5^5+..+5^97+5^99)
    24C=5^101 -5
    C=(5^101 -5)/24

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

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