1/1x3+1/3x5+1/5x7.....1/2009x2011+1/2011x2013=1/2×﹙1－1/3+1/3-1/5······+1/2009-1/2011+1/2011-1/2013)=1/2×﹙1-1/2013﹚=1006/2013
