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

Toán Lớp 7: so sánh A = 2 mũ 0 + 2 mũ 1+ 2 mũ 2+ -..+ 2 mũ 100 và B = 2 mũ 101

Toán Lớp 7: so sánh
A = 2 mũ 0 + 2 mũ 1+ 2 mũ 2+ ……+ 2 mũ 100 và B = 2 mũ 101

Comments ( 2 )

  1. A = 2^0 + 2^1 + 2^2 + … +2^{100}
    -> 2A = 2^1 + 2^2 + 2^3 + … + 2^{100} + 2^{101}
    -> 2A – A = (2^1 + 2^2 + 2^3 + … + 2^{100} + 2^{101}) – ( 2^0 + 2^1 + 2^2 + … +2^{100})
    -> A = 2^{101} – 2^0 = 2^{101} -1 < 2^{101}
    -> A < B 

  2. Giải đáp:
    A=2^0+2^1+2^2+…..+2^100
    =>2A=2^1+2^2+2^3+….+2^101
    =>2A-A=A=2^101-1
    Vì 2^101-1<2^101
    =>A<B.

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