7/6+13/12+21/20+31/30+…+421/420
来源：学生作业帮助网 编辑：六六作业网 时间：2024/05/10 10:56:52
7/6+13/12+21/20+31/30+…+421/4207/6+13/12+21/20+31/30+…+421/4207/6+13/12+21/20+31/30+…+421/420原式=1+1/
7/6+13/12+21/20+31/30+…+421/420
7/6+13/12+21/20+31/30+…+421/420
7/6+13/12+21/20+31/30+…+421/420
原式= 1 + 1/(2*3) + 1 +1/(3*4) + 1 +1/(4*5) + .+ 1 +1/(20*21)
=19 + (1/2 -1/3) + (1/3 -1/4) +（1/4 -1/5) + .+ (1/20 -1/21)
= 19 + 1/2 -1/21
=19又19/42
7/6+13/12+21/20+31/30+…+421/420
=1+1/6+1+1/12+1+1/20+....+1+1/420
=(1+1+1+。。。+1)+[1/(2*3)+1/(3*4)+1/(4*5)+....+1/(20*21)]
=19+(1/2-1/3+1/3-1/4+1/4-1/5+....+1/20-1/21)
=19+1/2-1/21
=19+19/42
=19又19/42
=(1+1/6)+(1+1/12)+(1+1/20)+(1+1/30)....+(1+1/420)
=(1+1/2-1/3)+(1+1/3-1/4)+(1+1/4-1/5)...(1+1/20-1/21)
=19+1/2-1/21=?
19又19/42
7/6+13/12+21/20+31/30+.421/420
3/2+7/6+13/12+21/20+31/30（简便计算）.
3/2+7/6+13/12-21/20+31/30-43/42+57/56+73/72
6-2分之3-6分之7-12分之13-20分之21-30分之31=?简算
7/6+13/12+21/20+31/30+43/42+57/56 7/6+13/12+21/20+31/30+43/42+57/56
2/3+7/6+12/13+20/21+30/31+……+9702/9703+9900/9901请详细解说,
2分之3+6分之7+12分之13+20分之21+30分之31+42分之43=
6分之7+12分之13+20分之21+30分之31+~+420分之421
7/6+13/12+21/20+31/30+…+421/420
7/6+13/12+21/20+31/30+43/42=
6分之7+12分之13 +20分之21+30分之31+42分之43=?
小学简便方法运算!1.（17/11+18/21+19/31+20/41）×（18/21+19/31+20/41+21/51）-（17/11+18/21+19/31+20/41+21/51）×（18/21+19/31+20/41）2.3/（1×5）+3/（5×9）+3/（9×13）+3/（13×17）+…+3/（17×21）3.5/6-7/12+9/20-11/30+13/42
12÷7×3/14 怎么简算?1/6 + 13/12 + 21/20 + 31/30 + 1/42 + 57/56怎么简算？
7/6 + 13/12 +21/20+31/30+43/42+57/56+73/72+91/90 简便计算
7/6+13/12+21/20+30/31+42/43+57/56+73/72+91/90=?
7/6+13/12+21/20+31/30+43/42+57/56+73/72+93/92=?
((-14/5)^4*(-10/7)^3*(-5/12)^2*(-3/20)^1)/|5/6-13/12+19/20-31/30|
1,3,7,13,21,31,43,( )