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1/(1*3)+1/(3*5)+1/(5*7)+.1/(1993*1995)+1/(1995*1997)
题目详情
1/(1*3)+1/(3*5)+1/(5*7)+.1/(1993*1995)+1/(1995*1997)
▼优质解答
答案和解析
1/(1*3)+1/(3*5)+1/(5*7)+.1/(1993*1995)+1/(1995*1997)
= 0.5 ( 1 - 1/3 ) + 0.5 ( 1/3 - 1/5 ) + 0.5 ( 1/5 - 1/7 ) + … + 0.5 ( 1/1993 - 1/1995 ) + 0.5 ( 1/1995 - 1/1997)
= 0.5 ( 1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 + … + 1/1993 - 1/1995 + 1/1995 - 1/1997 )
= 0.5 ( 1 - 1/1997 )
= 998/1997
= 0.5 ( 1 - 1/3 ) + 0.5 ( 1/3 - 1/5 ) + 0.5 ( 1/5 - 1/7 ) + … + 0.5 ( 1/1993 - 1/1995 ) + 0.5 ( 1/1995 - 1/1997)
= 0.5 ( 1 - 1/3 + 1/3 - 1/5 + 1/5 - 1/7 + … + 1/1993 - 1/1995 + 1/1995 - 1/1997 )
= 0.5 ( 1 - 1/1997 )
= 998/1997
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