Răspunsuri

2014-09-24T22:06:07+03:00
Se grupeaza 2-1 + 3-1 + ... + 2012-2011=
                       1+ 1 + 1 + ... + 1 = 1 x (2012-2) : 2 + 1
                                                  = 1 x  (2000 : 2+1)
                                                  = 1 x 1001
                                                   = 1001