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1/(1*3)+1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)=?需要详细的计算步骤。
1/(1*3)+1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)=?需要详细的计算步骤。
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第1个回答 2015-10-31
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您好,第一个步骤怎么出来的能否再分析一下,谢谢!
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第2个回答 2015-10-31
1/(1*3)+1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)=
=(1/1-1/3)/2+(1/3-1/5)/2+...+(1/9-1/11)/2
=(1/1-1/3+1/3-1/5...+1/9-1/11)/2
=(1-1/11)/2
=5/11
第3个回答 2015-10-31
1/(1*3)+1/(3*5)+1/(5*7)+1/(7*9)+1/(9*11)
=1/2*(2/(1*3)+2/(3*5)+2/(5*7)+2/(7*9)+2/(9*11))
=1/2*((1/1-1/3)+(1/3-1/5)+(1/5-1/7)+(1/7-1/9)+(1/9-1/11))
=1/2*(1/1-1/11)
=1/2*(10/11)
=5/11本回答被提问者采纳
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