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Question: If A = \(\begin{bmatrix} –1 & –2 & –2 \\ 2 & 1 & –2 \\ 2 & –2 & 1 \end{bmatrix}\), then adj A =...

If A = [–1–2–221–22–21]\begin{bmatrix} –1 & –2 & –2 \\ 2 & 1 & –2 \\ 2 & –2 & 1 \end{bmatrix}, then adj A =

A

A

B

AT

C

3A

D

3AT

Answer

3AT

Explanation

Solution

Adj A = $\begin{bmatrix}

  • (–3) & –6 & + (–6) \ –(–6) & + 3 & –6 \
  • 6 & –6 & + 3 \end{bmatrix}$

= 3 [–122–21–2–2–21]′\begin{bmatrix} –1 & 2 & 2 \\ –2 & 1 & –2 \\ –2 & –2 & 1 \end{bmatrix}^{'}

= 3. AT