\subsection{Riconoscere una quadrica}
$x^2 - 6xy - 4xz - 8y + 2z = 0$
\begin{tabularx}{\textwidth}{llX}
$
A = \left[
\arraycolsep=2.0pt\def\arraystretch{1.0}
\begin{array}{@{}ccc@{}}
1 & -3 & -2 \\
-3 & 0 & 0 \\
-2 & 0 & 0 \\
\end{array}
\right]
$ &
$
B = \left[
\arraycolsep=2.0pt\def\arraystretch{1.0}
\begin{array}{@{}cccc@{}}
1 & -3 & -2 & 0 \\
-3 & 0 & 0 & -4 \\
-2 & 0 & 0 & 1 \\
0 & -4 & 1 & 0
\end{array}
\right]
$ &
$\det A = 0$ \newline
$\det B = 121$ \newline
\end{tabularx}
$\det B > 0$ e $\det A = 0 \Rightarrow$ paraboloide iperbolico
