物欲泛滥
春芽
共回答了18个问题采纳率:100% 举报
1/2+5/6+11/12+19/20+29/30+41/42+55/56+71/72+89/90
=1-1/2+1-1/6+1-1/12+1-1/20+1-1/30+1-1/42+1-1/56+1-1/72+1-1/90
=9-﹙1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90﹚
=9-﹙1-1/2+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﹚
=9-﹙1-1/9﹚
=9-1+1/9
=8又1/9.
1年前
1