1 又1/2-2又5/6+3又1/12-4又19/20-5又1/30+6又41/42-7又1/56+8又71/72-9 又1/90等于多少?

1 又1/2-2又5/6+3又1/12-4又19/20-5又1/30+6又41/42-7又1/56+8又71/72-9 又1/90等于多少?
1 又1/2-2又5/6+3又1/12-4又19/20-5又1/30+6又41/42-7又1/56+8又71/72-9 又1/90等于多少?

1 又1/2-2又5/6+3又1/12-4又19/20-5又1/30+6又41/42-7又1/56+8又71/72-9 又1/90等于多少?
1 又1/2-2又5/6+3又1/12-4又19/20-5又1/30+6又41/42-7又1/56+8又71/72-9 又1/90
=(1-2+3-4-5+6-7+8-9)+(1/2-5/6+1/12-19/20-1/30+41/42-1/56+71/72-1/90)
=-9+(1/2-1+1/6+1/12-1+1/20-1/30+1-1/42-1/56+1-1/72-1/90)
=-9+(1-1/2+1/2-1/3+1/3-1/4+1/4-1/5-1/5+1/6-1/6+1/7-1/7+1/8-1/8+1/9-1/9+1/10)
=-9+1-2/5+1/10
=-8又3/10