作业帮1/30+1/42+1/56+1/72+1/90
来源：学生作业帮 编辑：作业帮 分类：数学作业 时间：2024/05/16 15:50:50
1/30+1/42+1/56+1/72+1/90
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)
=(7+5)/(5*6*7)+(9+7)/(7*8*9)+1/(9*10)
=12/(5*6*7)+16/(7*8*9)+1/(9*10)
=2/(5*7)+2/(7*9)+1/(9*10)
=2*(9+5)/(5*7*9)+1/(9*10)
=28/(5*7*9)+1/(9*10)
=4/(5*9)+1/(9*10)
=(8+1)/(9*10)
=1/10
=1/(5*6)+1/(6*7))+1/(7*8)+)+1/(8*9))+1/(9*10)
=(7+5)/(5*6*7)+(9+7)/(7*8*9)+1/(9*10)
=12/(5*6*7)+16/(7*8*9)+1/(9*10)
=2/(5*7)+2/(7*9)+1/(9*10)
=2*(9+5)/(5*7*9)+1/(9*10)
=28/(5*7*9)+1/(9*10)
=4/(5*9)+1/(9*10)
=(8+1)/(9*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=?
1/12+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
1/20+1/30+1/42+1/56+1/72+1/90
1/30+1/42+1/56+1/72+1/90+1/110简便算法（过程）
1/30+1/42+1/56+1/72+1/90+1/110=?
20/1+30/1+42/1+56/1+72/1+90/1救简算
算1/20+1/30+1/42+1/56+1/72+1/90
1/42+1/56+1/72+1/90+1/110
42/1+1/56+1/72+1/90+1/110