Toán Lớp 6: C= 1/1*7+1/7*13+1/13*19+…+1/2005*2011
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Toán Lớp 6: C= 1/1*7+1/7*13+1/13*19+…+1/2005*2011
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Answer
C = 1/{1 xx 7} + 1/{7 xx 13} + 1/{13 xx 19} + … + 1/{2005 xx 2011}
C = 6/6 . (1/{1 xx 7} + 1/{7 xx 13} + 1/{13 xx 19} + … + 1/{2005 xx 2011})
C = 1/6 . (6/{1 xx 7} + 6/{7 xx 13} + 6/{13 xx 19} + … + 6/{2005 xx 2011})
C = 1/6 . (1 – 1/7 + 1/7 – 1/13 + 1/13 – 1/19 + … + 1/2005 – 1/2011)
C = 1/6 . (1 – 1/2011)
C = 1/6 . (2011/2011 – 1/2011)
C = 1/6 . 2010/2011
C = 335/2011
$\text{Vậy}$ C = 335/2011
Giải đáp + Lời giải và giải thích chi tiết:
C=1/(1.7)+1/(7.13)+1/(13.19)+…+1/(2005.2011)
C=1/1-1/7+1/7-1/13+1/13-1/19+…+1/2005-1/2011
C=1/1-1/2011
C=2010/2011
Vậy C=2010/2011