2/1+6/1+12/1+20/1+30/1+42/1简算急!越详细,越好!
问题描述：
2/1+6/1+12/1+20/1+30/1+42/1简算
急!越详细,越好!
答
2/1+6/1+12/1+20/1+30/1+42/1
=2+6+12+30+42
=8+12+30+42
=50+42
=92
答
=1/2+(1/2-1/3)+(1/3-1/4).......-1/7
=5/14
答
楼主打错题了
1/2=1-1/2
1/6=1/2-1/3
1/12=1/3-1/4
1/20=1/4-1/5
1/30=1/5-1/6
1/42=1/6-1/7
相加=1-1/7=6/7
答
反了吧
1-1/2+1/2-1/3+1/3-1/4+1/4-1/5+1/5-1/6+1/6-1/7=1-1/7=6/7