30/1+42/1+56/1+72/1+90/1=?

来源：学生作业帮编辑：作业帮分类：数学作业时间：2024/07/15 00:34:03

30/1+42/1+56/1+72/1+90/1=?
请写出主要过程.
错了.
应该是1/30+1/42+1/56+1/72+1/90=?

是1/30+1/42+1/56+1/72+1/90吧
1/30+1/42+1/56+1/72+1/90
=1/(5*6)+1/(6*7)+1/(7*8)+1/(8*9)+1/(9*10)
=1/5-1/6+1/6-1/7+1/7-1/8+1/8-1/9+1/9-1/10
=1/5-1/10
=1/10

1/30+1/42+1/56+1/72+1/90 1/12+1/20+1/30+1/42+1/56+1/72+1/90=? 1/30+1/42+1/56+1/72+1/90+1/110=? 1/30+1/42+1/56+1/72+1/90=简便计算 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=多少 1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=______ 1/20+1/30+1/42+1/56+1/72+1/90+1/110+1/132=? 1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90=? 1/12+1/20+1/30+1/42+1/56+1/72+1/90 20/1+30/1+42/1+56/1+72/1+90/1 用简便方法计算. 1\30+1\42+1\56+1\72+1\90+1\110,简便计算