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

Toán Lớp 6: Tính nhanh: 1/100 – 1/100×99 – 1/99×98 – 1/98×97 – … – 1/3×2 – 1/2×1.

Toán Lớp 6: Tính nhanh:
1/100 – 1/100×99 – 1/99×98 – 1/98×97 – … – 1/3×2 – 1/2×1.

Comments ( 2 )

  1. #laviken#
    1/100 – 1/(100.99) – 1/(99.98) – 1/(98.97) – … – 1/(3.2) – 1/(2.1)
    =1/100-(1/(100.99)+1/(99.98)+1/(98.97)+…+1/(3.2)+1/(2.1))
    =1/100-(1/(1.2)+1/(2.3)+…+1/(97.98)+1/(98.99)+1/(99.100))
    =1/100-(1-1/2+1/2-1/3+….+1/97-1/98+1/98-1/99+1/99-1/100)
    =1/100-(1-1/100)
    =1/100-(100/100-1/100)
    =1/100-99/100
    =-98/100=-49/50

  2. Giải đáp:
     
    Lời giải và giải thích chi tiết:
    1/100 – 1/100.99 – 1/99.98 – 1/98.97 -………..- 1/3.2 – 1/2.1
    = 1/100 – ( 1/1.2 + 1/2.3 +…..+ 1/97.98 + 1/98.99 + 1/99.100 )
    = 1/100 – ( 1 – 1/2 + 1/2 – 1/3 +….+ 1/97 – /98 + 1/98 – 1/99 + 1/99 – 1/100 )
    = 1/100 – ( 1 – 1/100 )
    = 1/100 – 99/100
    = -98/100 = -49/50
    #haducdung2009 

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

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