Question

If A =$$\left[\begin{array}{ccc}3& -3& 4\\ 2& -3& 4\\ 0& -1& 1\end{array}\right]$$ , then adj (adj A ) is equal to

• A. A
• B. I
• C. O
• D. none of these

Answer 1

The correct option is A A

$\begin{array}{c}A=\left[\begin{array}{ccc}3& -3& 4\\ 2& -3& 4\\ 0& -1& 1\end{array}\right]\\ adjA=\left[\begin{array}{ccc}1& -2& -2\\ -1& 3& 3\\ 0& -4& -3\end{array}\right]\\ =\left[\begin{array}{ccc}1& -1& 0\\ -2& 3& -4\\ -2& 3& -3\end{array}\right]\\ adj\left(adjA\right)=\left[\begin{array}{ccc}3& 2& 0\\ -3& -3& -1\\ 4& 4& 1\end{array}\right]\\ adj\left(adjA\right)=\left[\begin{array}{ccc}3& -3& 4\\ 2& -3& 4\\ 0& -1& 1\end{array}\right]=A\end{array}$

option A is the correct answer