Determinante di $$$\left[\begin{array}{cc}9 - \lambda & 2\\2 & 6 - \lambda\end{array}\right]$$$

Calcola $$$\left|\begin{array}{cc}9 - \lambda & 2\\2 & 6 - \lambda\end{array}\right|$$$.

Il determinante di una matrice 2x2 è $$$\left|\begin{array}{cc}a & b\\c & d\end{array}\right| = a d - b c$$$.

$$$\left|\begin{array}{cc}9 - \lambda & 2\\2 & 6 - \lambda\end{array}\right| = \left(9 - \lambda\right)\cdot \left(6 - \lambda\right) - \left(2\right)\cdot \left(2\right) = \lambda^{2} - 15 \lambda + 50$$$

$$$\left|\begin{array}{cc}9 - \lambda & 2\\2 & 6 - \lambda\end{array}\right| = \left(\lambda - 10\right) \left(\lambda - 5\right)$$$A