If $A=\begin{bmatrix} 1 & 2\\ 1 & 3\\ \end{bmatrix}$, then $Adj A$ is equal to
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → $Adj A=\begin{bmatrix} 3 & -2\\ -1 & 1\\ \end{bmatrix}$
$A=\begin{bmatrix} 1 & 2\\ 1 & 3\\ \end{bmatrix}$
B = Co-factor matrix = $\begin{bmatrix} 3 & -1\\ -2 & 1\\ \end{bmatrix}$
$Adj A=B^T=\begin{bmatrix} 3 & -2\\ -1 & 1\\ \end{bmatrix}$