Avem o suma gauss, care se poate calcula cu formula:
[tex] 1+2+3+\ldots + n=\dfrac{n(n+1)}{2} [/tex]
Dacă [tex] E(x) =x+2 [/tex] atunci
[tex] E(1)+E(2)+E(3)+\ldots+E(25) = \\ = (1+2)+(2+2)+(3+2)+\ldots+(2+25) \\ = 3+4+5+\ldots+27 \\ =1+2+3+\ldots +27 -1-2 \\ = \dfrac{27\cdot 28}{2} -3 \\ = 27\cdot14-3 \\ =378-3 \\ \tt = 375 [/tex]
