分子:1-1/2+1/3-1/4+1/5-1/6+1/7-1/8
=(1-1/2-1/4-1/8)+(1/3-1/6)+1/5+1/7
=1/8+1/6+1/5+1/7
所以:(1-1/2+1/3-1/4+1/5-1/6+1/7-1/8)/(1/5+1/6+1/7+1/8)=1
1-1/2+1/3-1/4+1/5-1/6+1/7-1/8=1/5+(1/3-1/6)+1/7+(1-1/2-1/4-1/8)
=1/5+1/6+1/7+1/8
所以(1-1/2+1/3-1/4+1/5-1/6+1/7-1/8)/(1/5+1/6+1/7+1/8)=1
等于1