1/2 1/10 1/30 1/68
1、 1,2,10,30,68() 2、4,5,8,10,() 3、-1,0,1,2,9,() 4、2,3,13,175
(1/2-1/3)+(1/4-1/5)+(1/7-1/10)+(1/14-1/15)+(1/28-1/30)
1/2+1/6+1/12+1/20+1/30+1/42+1/56+1/72+1/90+1/10
(1/2-1/3)+(1/4-1/5)+(1/7-1/10)+(1/14-1/15)+(1/28-1/30))
(1/2+1/4+1/6+1/10+1/12+1/60)/(1+1/3+1/5+1/10+1/15+1/30)
1/2+1/6+1/10+1/12+1/20+1/30+1/42+.+1/2008*2009
(1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)(用简算)
(1+1/3+1/5+1/10+1/15+1/30)/(1/2+1/4+1/6+1/12+1/20+1/60)=R
简算:(1+1/3+1/5+1/10+1/15+1/30)÷(1/2+1/4+1/6+1/12+1/20+1/60)=?
(1+1/3+1/5+1/10+1/15+1/30)÷(1/2+1/4+1/6+1/12+1/20+1/60)
-1,+1/2,-1/3,+1/4,-1/5,+1/6,-1/7,+1/8,-1/9,+1/10,-1/11,.第30个
(1/2-1/3) (1/4-1/5) (1/7-1/10) (1/14-1/15) (1/28 1/30)怎么算