1/3×1+1/3×5+1/5×7…1/2009×2011等于多少
问题描述：
1/3×1+1/3×5+1/5×7…1/2009×2011等于多少
答
=1/2sigman=2^2010[1/(n-1)-1/(n+1)]=1/2(1-1/2011)=1005/2011
答
简便计算
1/3×1+1/3×5+1/5×7…1/2009×2011
=1/2x(1-1/3)+1/2x(1/3-1/5)+1/2x(1/5-1/7)+...+1/2x(1/2009-1/2011)
=1/2x(1-1/2011)
=1005/2011