Răspuns :
(2013-7)/2+1=2006/2+1=1004(nr elemte)
7-5+9-7+...+2013-2011=
=2+2+2+...+2=
=2*1004=2008
7 + 9 + 11 +.. + 2013 - 5 - 7 - 9- .. - 2011=
= (7-7) + .. + (2011-2011) + 2013 - 5
= 2013 - 5
= 2008
(2013-7)/2+1=2006/2+1=1004(nr elemte)
7-5+9-7+...+2013-2011=
=2+2+2+...+2=
=2*1004=2008
7 + 9 + 11 +.. + 2013 - 5 - 7 - 9- .. - 2011=
= (7-7) + .. + (2011-2011) + 2013 - 5
= 2013 - 5
= 2008