1/3+1/15+1/35+1/63+1/99+1/143为什么=(1-1/13)*1/2=6/13

问题描述:

1/3+1/15+1/35+1/63+1/99+1/143为什么=(1-1/13)*1/2=6/13

1/3+1/15+1/35+1/63+1/99+1/143=1/2×(1-1/3)+1/2×(1/3 -1/5)+1/2×(1/5-1/7)+1/2×(1/7-1/9)+1/2×(1/9-1/11)+1/2×(1/11-1/13)=1/2×(1-1/3+1/3-1/5······+1/11-1/13)=1/2×(1-1/13)=1/2×...