1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
来源:学生作业帮助网 编辑:作业帮 时间:2024/07/02 00:33:09
![1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120](/uploads/image/z/1685042-26-2.jpg?t=1%2F3%2B1%2F6%2B1%2F10%2B1%2F15%2B1%2F21%2B%60%60%60%60%60%60%60%2B1%2F105%2B1%2F120)
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
=1/2(1/2-1/3+1/3-1/4+…………+1/15-1/16)
=1/2(1/2-1/16)
=7/32
1/3+1/6+1/10+1/15+1/21+```````+1/105+1/120
=2(1/2-1/3+1/3-1/4+…………+1/15-1/16)
=2(1/2-1/16)
=7/8