1/枣没8+1/24+1/48+1/毕粗80+1/120
=(1/2-1/4)/2+(1/4-1/6)/2+(1/手岩镇6-1/8)/2+(1/8-1/10)/2+(1/10-1/12)/2
=[(1/2-1/4)+(1/4-1/6)+(1/6-1/8)+(1/8-1/10)+(1/10-1/12)]/2
=(1/2-1/12)/2、
=(5/12)/2、
=5/24
1/8+1/24+1/48+1/120
=(30+10+5+2)/240
=47/240
1/8+1/24+1/48+1/120
=1/2*(1/2-1/4)+1/2*(1/4-1/6)+1/2*(1/6-1/8)+1/2*(1/8-1/10)
=1/2*(1/2-1/悔缓4+1/4-1/碧衫模6+1/6-1/塌拍8+1/8-1/10)
=1/2*(1/2-1/10)
=1/2*(5/10-1/10)
=1/2*2/5
=1/5