1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72得多少(要分数)
问题描述:
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72得多少(要分数)
答
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72
=(1-1/2)+(1/2-1/3)+(1/3-1/4)+...+(1/8-1/9)
=1-1/9
=8/9