Question

If $A=\left[\begin{array}{cc}4& 2\\ 3& 3\end{array}\right]$, then adj (adj $A$) is equal to

• A. $\left[\begin{array}{cc}3& -2\\ -3& 4\end{array}\right]$
• B. $\left[\begin{array}{cc}4& 2\\ 3& 3\end{array}\right]$
• C. $6\left[\begin{array}{cc}4& 2\\ 3& 3\end{array}\right]$
• D. None of these

Answer 1

Answer: (B)

$\left[\begin{array}{cc}4& 2\\ 3& 3\end{array}\right]$

For $A=\left[\begin{array}{cc}4& 2\\ 3& 3\end{array}\right]$
$adj\left(A\right)=\left[\begin{array}{cc}3& -3\\ -2& 4\end{array}\right]$
$adj\left(adj\left(A\right)\right)=\left[\begin{array}{cc}4& 2\\ 3& 3\end{array}\right]$