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

Toán Lớp 5: 1/2+1/4+1/8+1/16+=…+1/1024

Toán Lớp 5: 1/2+1/4+1/8+1/16+……………+1/1024

Comments ( 2 )

  1. Lời giải và giải thích chi tiết:
    Đặt  A = 1/2 + 1/4 + 1/8 + 1/16 + ………….. + 1/1024
    A = 1/2 + 1/(2^2) + 1/(2^3) + ……….. + 1/(2^10)
    2A = 1 + 1/2 + 1/(2^2) + ………… + 1/(2^9)
    A = 1 – 1/(2^10)

  2. A x 2 = 1 – ( 1/2 + 1/4 + 1/8 + 1/16 + .. + 1/1024 ) – 1/1024
    A x 2 = 1 – 1/1024 + A
    A x 2 – A = 1- 1/1024
    A = 1 – 1/1024
    A = 1023/1024
     

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