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

Toán Lớp 6: A = 2 + 2^2 + 2^3 + 2^4 + … + 2^98 + 2^99 + 2^100 Tính tổng A

Toán Lớp 6: A = 2 + 2^2 + 2^3 + 2^4 + … + 2^98 + 2^99 + 2^100
Tính tổng A

Comments ( 2 )

  1. A = 2 + 2^2 + 2^3 + 2^4 + … + 2^[98] + 2^[99] + 2^[100]
    2A = 2 ( 2 + 2^2 + 2^3 + 2^4 + … + 2^[98] + 2^[99] + 2^[100] )
    2A = 2^2 + 2^3 + 2^4 + 2^5 + … + 2^[99] + 2^[100] + 2^[101]
    2A – A = ( 2^2 + 2^3 + … + 2^[100] + 2^[101] ) – ( 2 + 2^2 + … + 2^[99] + 2^[100] )
    A = 2^[101] – 2

  2. Giải đáp+Lời giải và giải thích chi tiết:
    A=2+2^2+2^3+2^4+…..+2^98+2^99+2^100
    2A=2( 2+2^2+2^3+2^4+…..+2^98+2^99+2^100)
    2A=2^2+2^3+2^4+2^5+….+2^99+2^100+2^101
    2A-A=(2^2+2^3+2^4+2^5+….+2^99+2^100+2^101)-(2+2^2+2^3+2^4+…..+2^98+2^99+2^100)
    A=2^2+2^3+2^4+2^5+…+2^99+2^100+2^101-2-2^2-2^3-2^4-…-2^98-2^99-2^100
    A=(2^2-2^2)+(2^3-2^3)+(2^4-2^4)+…+(2^99-2^99)+(2^100-2^100)+2^101-2
    A=2^101-2
    Vậy A=2^101-2

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

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