求1x2,2x3,3x4,4x5.99x100.前99项的倒数之和._数学解答

求1x2,2x3,3x4,4x5.99x100.前99项的倒数之和.

人气：476 ℃　时间：2020-03-28 06:05:51

解答

1/（1x2）=1/1-1/2
1/(2x3)=1/2-1/3
1/(3x4)=1/3-1/4
.
1/(98x99)=1/98-1/99
1/(99x100)=1/99-1/100
之和为1/1-1/100=99/100