1/6+1/12+1/20+1/30+1/42+1/52+1/72

来源:学生作业学帮网 编辑:学帮网 时间:2024/06/18 03:51:39

1/6+1/12+1/20+1/30+1/42+1/52+1/72

=1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9
=1/2-1/9
=7/18