15问答网 > 1+3分之1-12分之7+20分之9-30分之11+42分之13-56分之15的简便算法

1+3分之1-12分之7+20分之9-30分之11+42分之13-56分之15的简便算法

2024-12-04 20:47:22

推荐回答（4个）

回答1：

1+1/3-7/12+9/20-11/30+13/42-15/56
=1+1/3-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)
=1+1/3-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7-1/7-1/8
=1+(1/3-1/3)-(1/4-1/4)+(1/5-1/5)-(1/6-1/6)+(1/7-1/7)-1/8
=1+0-0+0-0+0-1/8
=1-1/8
=7/8
=8分之7

回答2：

1+1/3-7/12+9/20-11/30+13/42-15/56
=1+1/3-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)
=1+1/3-1/3-1/4+1/4+1/5-1/5-1/6+1/6+1/7-1/7-1/8
=1-1/8
=7/8

回答3：

1+1/3 -7/12 +9/20 -11/30 +13/42 -15/56
1+1/3 -7/（3×4） +9/(4×5) -11/(5×6 )+13/(6×7) -15/(7×8_
=1+1/3 -1/3-1/4 +1/4+1/5 -1/5-1/6 +1/6+1/7 -1/7-1/8
=1-1/8=7/8

回答4：

=1+1/3-(1/3+1/4)+(1/4+1/5)-(1/5+1/6)+(1/6+1/7)-(1/7+1/8)
=1-1/8
=7/8