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已知a=-2,b=-1,求1/ab+1/(a-1)(b-1)+1/(a-2)(b-2)+.+1/(a-2009)(b-2009)的值
人气:405 ℃ 时间:2020-04-05 02:51:50
解答
1/ab+1/(a-1)(b-1)+1/(a-2)(b-2)+.+1/(a-2009)(b-2009)的值
=1/(-1)(-2)+1/(-2)(-3)+(-3)(-4)+……+1/(-2010)(-2011)
=1/1-1/2+1/2-1/3+1/3-1/4+……+1/2010-1/2011
=1-(1/2011)
=2010/2011
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