云南创新pp条:20/1+30/1+42/1+56/1+72/1+90/1
来源:百度文库 编辑:中科新闻网 时间:2024/04/27 21:16:47
是分数简便方法计算.我一时忘了怎么算了.请教一下.谢了哦.
题目打错拉,分子在前,分母在后,下面就按照正确的分数去解题!
原题=(1/4-1/5)+(1/5-1/6)+(1/6-1/7)+(1/7-1/8)+(1/8-1/9)+(1/9-1/10)
=1/4-1/10
=3/20
20/1+30/1+42/1+56/1+72/1+90/1
1/20+1/30+1/42+1/56+1/72+1/90
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=?
有一列数:1/2,1/6,1/12,1/20,1/30,1/42……
1/30+1/42+1/72+1/90+…1/9900
巧算 1/30+1/42+1/56+1/72+1/90
30/1+42/1+56/1+72/1+90/1=?
谁能巧算1-1/2-1/6-1/12-1/20-1/30-1/42-1/56-1/72-1/90
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=______