1/2+1/6+1/12+1/20+1/30----1/90=?

来源：学生作业帮助网编辑：作业帮时间：2024/11/17 17:46:17

1/2+1/6+1/12+1/20+1/30----1/90=?
1/2+1/6+1/12+1/20+1/30----1/90=?

1/2+1/6+1/12+1/20+1/30----1/90=?
=1/1*2+1/2*3+1/3*4+……+1/9*10
=1-1/2+1/2-1/3+1/3-1/4+……+1/9-1/10
=1-1/10
=9/10

eeag

1/2+1/6+1/12+1/20+1/30----1/90
=1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+...1/9-1/10
=1-1/10
=9/10