1-1/2+1/6+1/12+1/20+...+1/72+1/90
来源：学生作业帮助网 编辑：六六作业网 时间：2024/11/24 05:10:00
1-1/2+1/6+1/12+1/20+...+1/72+1/901-1/2+1/6+1/12+1/20+...+1/72+1/901-1/2+1/6+1/12+1/20+...+1/72+1/90原
1-1/2+1/6+1/12+1/20+...+1/72+1/90
1-1/2+1/6+1/12+1/20+...+1/72+1/90
1-1/2+1/6+1/12+1/20+...+1/72+1/90
原式=1-[（1-1/2）+(1/2-1/3)+(1/3-1/4)+...+(1/8-1/9)+(1/9-1/10)]
=1-(1-1/10)
=1/10