Salut,
Determinantul matricii este:
[tex]detA=\begin{vmatrix}1 & -1 & -1\ \\ 1 & 3 & -1\ \\ m & 0 & 2\ \end{vmatrix}=\\\\=1\cdot 3\cdot 2+1\cdot 0\cdot (-1)+m\cdot (-1)\cdot (-1)-m\cdot 3\cdot (-1)-0\cdot (-1)\cdot 1-1\cdot (-1)\cdot 2=\\=6+m+3m+2=4m+8\neq0,\ sau\ m\neq-2.\ Deci\ m\in\mathbb{R}\ \backslash\ \{-2\}.[/tex].
Green eyes.
