1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+……+1/(2007*2008*2009)=?

问题描述:

1/(1*2*3)+1/(2*3*4)+1/(3*4*5)+……+1/(2007*2008*2009)=?
1个回答 分类:数学 2014-10-31

问题解答:

我来补答
1/1*2*3+1/2*3*4+1/3*4*5+1/4*5*6
=1/2*(1/1*2-1/2*3)+1/2*(1/2*3-1/3*4)+1/2*(1/3*4-1/4*5)+1/2*(1/4/5-1/5*6)
=1/2*(1/1*2-1/5*6)
=7/30
 
 
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