1/1*2+1/2*3+1/3*4+.......+1/2005*2006=?
来源:百度知道 编辑:UC知道 时间:2024/06/02 05:48:50
急
首先 我们知道 1/[n*(n+1)] = 1/n - 1/(n+1)
所以原式等于
1 - 1/2 + 1/2 - 1/3 + 1/3 - 1/4 + 1/4 …… + 1/2005 - 1/2006
=1 - 1/2006
=2005/2006
首先,原式=1/2+1/6+1/12+1/20+......+1/2005*2006
=1/2+1/2-1/3+1/3-1/4+1/4+1/5+...+1/2005-1/2006
=1-1/2006
=2005/2006
完毕!!
(1/2005-1)(1/2004-1)........(1/3-1)(1/2-1)
1+1/2+1/3+.....+1/n
1+1/2+1/3+...+1/100
1-1/2+1/3-.....-1/10
(1+1/2+1/3+1/4)×
(1-1/2)(1-1/3)(1-1/4)(1-1/5).....(1-1/1000)
1+1/(1+2)+1/(1+2+3)+...+1/(1+2+3+...+100)
1+1/(1+2)+1/(1+2+3)+-------+1/(1+2+3+----+100)
1+1/1+2+1/1+2+3+...+1/1+2+3...+2000
1+1/1+2+1/1+2+3.........+1/1+2+3.....100