12/1 + 23/1 + 34/1 +.+2930/1 /是分号,乘号,1 1 1 1 --- + --- + --- + .+----- = 12 23 34 29*30

来源：学生作业帮助网编辑：作业帮时间：2024/05/05 06:27:07

1*2/1 + 2*3/1 + 3*4/1 +.+29*30/1 /是分号,*乘号,1 1 1 1 --- + --- + --- + .+----- = 1*2 2*3 3*4 29*30
1*2/1 + 2*3/1 + 3*4/1 +.+29*30/1
/是分号,*乘号,1 1 1 1 --- + --- + --- + .+----- = 1*2 2*3 3*4 29*30

1*2/1 + 2*3/1 + 3*4/1 +.+29*30/1 /是分号,*乘号,1 1 1 1 --- + --- + --- + .+----- = 1*2 2*3 3*4 29*30
注意到：1/1*2=1-1/2 1/2*3=1/2-1/3 1/3*4=1/3-1/4 ...原式＝1-1/2+1/2-1/3+1/3-1/4+...+1/29-1/30 ＝1-1/30＝29/30

1+2+3+4+1 1 2 3 4 1 2 3 4 1 2 3 4 1,2,3,4, 1 2 3 4 1 2 3 4 1,2,3,4, 1,2,3,4, 1,2,3,4, 1,2,3,4, 1 2 3 4 1,2,3,4, 1,2,3,4, 1,2,3,4, 1、2、3、4 1+2+3×4 1,2,3,4