简算,急
来源:百度知道 编辑:UC知道 时间:2024/06/02 08:35:55
2分之1+6分之5+12分之11+20分之19+30分之29+42分之41
2分之1+6分之5+12分之11+20分之19+30分之29+42分之41
=1-1/2+1-1/6+1-1/12+1-1/20+1-1/30+1-1/42
=6-(1/2+1/6+1/12+1/20+1/30+1/42)
=6-[(1-1/2)+(1/2-1/3)+(1/3-1/4)+(1/4-1/5)+(1/5-1/6)+(1/6-1/7)]
=6-(1-1/7)
=5+1/7
=36/7
6-1/2-1/6-1/12-1/20-1/30-1/42=
2分之1+6分之5+12分之11+20分之19+30分之29+42分之41
=(1-1/2)+(1-1/2*3)+(1-1/3*4)+(1-1/4*5)+(1-1/5*6)+(1-1/6*7)
=6-(1/2+1/2*3+1/3*4+1/4*5+1/5*6+1/6*7)
=6-(1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7)
=6-(1-1/7)
=5+1/7