若x=1 y=2时
来源:百度知道 编辑:UC知道 时间:2024/07/04 22:41:34
xy分之一+(x+1)(y+1)之一+(X+2)(Y+2)分之一……+(x+2006)(y+2006)分之一的值!!!
将x=1 y=2带入,得原式=1/2+1/2*1/3+1/3*1/4+......+1/2007*1/2008
=1/2+1/2-1/3+1/3-1/4+1/4-1/5+.....+1/2006/-1/2007+1/2007-1/2008
=1/2+1/2-1/2008=2007/2008
1/2 + 1/(2*3) + 1/(3*4)+........+ 1/(2007*2008)
= 1/2 + (1/2 - 1/3 ) + (1/3 - 1/4) +........+ (1/2007 -1/2008)
=1/2 +1/2 - 1/2008
=2007/2008
解:
原式=1/2+1/6+1/15+……+1/2007*2008
=1-1/2+1/2-1/3+1/3-1/4……1/2007-1/2008
=1-1/2008
=2007/2008
答:2007/2008
注:a/b 就是a分之b
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