- 2014 ≤ x ≤ 2015 M = {- 2014,- 2013, ......-1, 0,1.........2014,2015}
a) S = 2015
b) Sm = |-2014| + |-2013| + ......+|-1| + |1| +......+|2014| + |2015| =
= 2(2014+2013 +.........+ 1) + 2015 = 2·2014·2015/2 + 2015 = 2015(2014+1)
Sm = 2015·2015 = 2015² = p.p.