$$$\left[\begin{array}{cc}4 & 7\\7 & 9\end{array}\right]$$$:n determinantti

Laske $$$\left|\begin{array}{cc}4 & 7\\7 & 9\end{array}\right|$$$.

2x2-matriisin determinantti on $$$\left|\begin{array}{cc}a & b\\c & d\end{array}\right| = a d - b c$$$.

$$$\left|\begin{array}{cc}4 & 7\\7 & 9\end{array}\right| = \left(4\right)\cdot \left(9\right) - \left(7\right)\cdot \left(7\right) = -13$$$

$$$\left|\begin{array}{cc}4 & 7\\7 & 9\end{array}\right| = -13$$$A