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

Toán Lớp 6: A=1/3+1/3^2+1/3^3+1/3^4+-+1/3^98+1/3^99

Tháng Hai 6, 2023 Toán học 2 Comments 0 views

Toán Lớp 6: A=1/3+1/3^2+1/3^3+1/3^4+….+1/3^98+1/3^99

Comments ( 2 )

  1. hienchaudiem
    hienchaudiem
    6 Tháng Hai, 2023 at 10:07 chiều
    Reply
    Giải đáp: A=1/2-1/(2.3^99)
    Lời giải và giải thích chi tiết:
    A=1/3+1/3^2+1/3^3+1/3^4+….+1/3^98+1/3^99
    3A=1+1/3+1/3^2+1/3^3+….+1/3^97+1/3^98
    2A=3A-A=(1+1/3+1/3^2+1/3^3+….+1/3^97+1/3^98)-(1/3+1/3^2+1/3^3+1/3^4+….+1/3^98+1/3^99)
    2A=1-1/3^99
    $A=\dfrac{2A}{2}=\dfrac{1-\dfrac{1}{3^{99}}}{2}$
    A=1/2-1/(2.3^99)
    Vậy A=1/2-1/(2.3^99)

  2. minhhaanh
    minhhaanh
    6 Tháng Hai, 2023 at 10:07 chiều
    Reply
    A = 1/3 + 1/3^2 + 1/3^3 + 1/3^4 + …. + 1/3^98 + 1/3^99
    3A = 1 + 1/3 + 1/3^2 + 1/3^3 + …. + 1/3^97 + 1/3^98
    3A – A = ( 1 + 1/3 + 1/3^2 + 1/3^3 + …. + 1/3^97 + 1/3^98 ) – ( 1/3 + 1/3^2 + 1/3^3 + 1/3^4 + …. + 1/3^98 + 1/3^99 )
    2A = 1 – 1/3^99
    2A= ( 3^99 – 1 )/3^99
    A = ( 3^99 – 1 )/3^99 : 2
    A = ( 3^99 – 1 )/( 3^99 . 2 )

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

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