[tex]\text{Metoda lui Sarrus:}\\ \\\left|\begin{array}{ccc}m&1&2\\2m&m-1&1\\3&m&m+3\end{array}\right| =\\ \left.\begin{array}{ccc}\,m&1&\,\,\,\,\,2\\\,\,2m&m-1&\,\,\,\,\,\,1\end{array}\right.\\\\\\ = m(m-1)(m+3)+(2m)\cdot m\cdot 2+3\cdot 1\cdot 1-\\ -2\cdot (m-1)\cdot 3-1\cdot m\cdot m-(m+3)\cdot 1\cdot (2m)\\ \\ = \boxed{m^{3}+3m^{2}-15m+9}[/tex]
