[tex]E(x)=-x^2+x+1[/tex]
Atunci suma se scrie
[tex]E(0)+\displaystyle\sum_{k=1}^{100}(-k^2+k+1)=\\=1-\sum_{k=1}^{100}k^2+\sum_{k=1}^{100}k+100[/tex]
Se folosesc sumele
[tex]\displaystyle\sum_{k=1}^nk^2=\frac{n(n+1)(2n+1)}{6}, \ \sum_{k=1}^nk=\frac{n(n+1)}{2}[/tex]
