Find $\text{adj } A$, if $A = \begin{bmatrix} 2 & -1 \\ 4 & 3 \end{bmatrix}$.
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → $\begin{bmatrix} 3 & 1 \\ -4 & 2 \end{bmatrix}$ ##
Given, $A = \begin{bmatrix} 2 & -1 \\ 4 & 3 \end{bmatrix}$
$C_{11} = 3, \quad C_{12} = -4$
$C_{21} = 1, \quad C_{22} = 2$
$\text{adj } A = \begin{bmatrix} C_{11} & C_{12} \\ C_{21} & C_{22} \end{bmatrix}^T = \begin{bmatrix} 3 & -4 \\ 1 & 2 \end{bmatrix}^T$
$\text{adj } A = \begin{bmatrix} 3 & 1 \\ -4 & 2 \end{bmatrix}$