Limita

[Francisc]

Sa se calculeze limita sirului :
\(
{\lim }\limits_{n \to \infty } \frac{1}{{n^2 }}\sum\limits_{k = 0}^{n - 1} {\sqrt {3k^2 + 3k + 1 + \frac{{n^2 }}{{a^2 }}} }
\ \), unde a>0.