1/8+1/24+1/48+1/80+1/120+1/168
=1/2*[(1/2-1/4)+(1/4-1/6)+(1/6-1/8)+(1/8-1/10)+(1/10-1/12)+(1/12-1/14)]
=1/2*[1/2-1/14]
=3/14
能看懂吧,
1/8+1/24+1/48+1/80+1/120+1/168
=1/2*[(1/2-1/4)+(1/4-1/6)+(1/6-1/8)+(1/8-1/10)+(1/10-1/12)+(1/12-1/14)]
=1/2*[1/2-1/14]
=3/14
能看懂吧,