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

Toán Lớp 6: Cho S=1+2+2mũ 2+…+2 mũ 2005 .Hãy so sánh S với 5.2 mũ 2004

Toán Lớp 6: Cho S=1+2+2mũ 2+…+2 mũ 2005 .Hãy so sánh S với 5.2 mũ 2004

Comments ( 1 )

  1. S = 1 + 2 + 2^2 + …. + 2^2005
    2S = 2 + 2^2 + 2^3 + …. + 2^2006
    2S – S = ( 2 + 2^2 + 2^3 + …. + 2^2006 ) – ( 1 + 2 + 2^2 + …. + 2^2005 )
    S = 2^2006 – 1
    Vì 2^2006 – 1 < 2^2006 < 2^2004 . 4 < 5 . 2^2004
    ⇒ S < 2^2004 . 5
    Vậy , S < 5 . 2^2004

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