1/2+1/3+1/4+..+1/2013
2012+2012/2+2011/3+...+1/2013
=1/2+1/3+1/4+...+1/2013
(2012/2+1)+(2011/3+1)+...+(1/2013+1)
=1/2+1/3+1/4+...+1/2013
2014/2+2014/3+...+2014/2013
=1/2+1/3+1/4+...+1/2013
2014(1/2+1/3+...+1/2013)
=1/2014
=1/2014 còn đâu tự làm nhé!!!!!!!!!!!!!^^^^^^^^^^^@@@@@@@########$$$$$$*********