Question

If \[A = \begin{bmatrix}3 & 1 \\ 2 & - 3\end{bmatrix}\], then find |adj A|.

Answer 1

\[\left| A \right| = \begin{vmatrix}3 & 1 \\ 2 & - 3\end{vmatrix} = - 11\]
\[ \therefore \left| adj A \right| = \left| A \right|^{n - 1} = \left( - 11 \right)^{2 - 1} = - 11\]