(-1x1/2)+(-1/2x1/3)+(-1/3x1/4)+……+(-1/2013x1/2014)
=-(1x1/2)-(1/2x1/3)-(1/3x1/4)-……-(1/2013x1/2014)
=-[(1x1/2)+(1/2x1/3)+(1/3x1/4)+……+(1/2013x1/2014)]
=-[(1-1/2)+(1/2-1/3)+(1/3-1/4)+……+(1/2013-1/2014)]
=-(1-1/2+1/2-1/3+1/3-1/4+……+1/2013-1/2014)
=-(1-1/2014)
=-2013/2014