|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+…+|1/30-1/29|| |是绝对值符号哦!
问题描述：
|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+…+|1/30-1/29|
| |是绝对值符号哦!
答
|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+…+|1/30-1/29|
=(1/20-1/21)+(1/21-1/22)+(1/22-1/23)+……+(1/29-1/30)
=1/20-1/21+1/21-1/22+1/22-1/23+……+1/29-1/30
=1/20-1/30
=3/60-2/60
=1/60
答
|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+…+|1/30-1/29| = 1/20-1/21+1/21-1/22+1/22-1/23+.....+1/29-1/30=1/20-1/30=1/60中间的都抵消了
答
|1/21-1/20|+|1/22-1/21|+|1/23-1/22|+…+|1/30-1/29|
＝1/20-1/21+1/21-1/22+…+1/29-1/30
＝1/20-1/30
＝1/60
（ |小数-大数|=大数-小数 ）
加油!有什么不懂的再问,诚答!