有理数的计算(1)1/1x4+1/4x7+1/7x10+...+1/2008x2011+1/2011x2014
问题描述：
有理数的计算
(1)1/1x4+1/4x7+1/7x10+...+1/2008x2011+1/2011x2014
答
用列项公式前面加个1/3过程为1/3(1-1/4+1/4-1/7...+1/2011-1/2014)=1/3x(1-1/2014)=671/2014
答
1/1x4+1/4x7+1/7x10+...+1/2008x2011+1/2011x2014
=(1-1/4+1/4-1/7+1/7-1/10+...+1/2008-1/2011+1/2011-1/2014)/3
=(1-1/2014)/3=671/2014