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CUET · MATHS · PYQ PAPER 2023

If \(A = \begin{bmatrix} 1 & 2 & -1 \\ 2 & 3 & 0 \\ 1 & -1 & 2 \end{bmatrix}\), then Adj(A) is:

  1. A \(\left[\begin{array}{ccc}1 & 2 & 1 \\ 2 & 3 & -1 \\ -1 & 0 & 2\end{array}\right]\)
  2. B \(\left[\begin{array}{ccc}6 & -4 & -5 \\ -3 & 3 & 3 \\ 3 & -2 & -1\end{array}\right]\)
  3. C \(\left[\begin{array}{ccc}6 & -3 & 3 \\ -4 & 3 & -2 \\ -5 & 3 & -1\end{array}\right]\)
  4. D \(\left[\begin{array}{ccc}1 & 2 & -1 \\ 2 & 3 & 0 \\ 1 & -1 & 2\end{array}\right]\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(\left[\begin{array}{ccc}6 & -3 & 3 \\ -4 & 3 & -2 \\ -5 & 3 & -1\end{array}\right]\)

Step-by-step Solution

Detailed explanation

\( C_{11} = (-1)^{1+1} \det \begin{vmatrix} 3 & 0 \\ -1 & 2 \end{vmatrix} = 6-0 = 6 \) \( C_{12} = (-1)^{1+2} \det \begin{vmatrix} 2 & 0 \\ 1 & 2 \end{vmatrix} = -(4-0) = -4 \) \( C_{13} = (-1)^{1+3} \det \begin{vmatrix} 2 & 3 \\ 1 & -1 \end{vmatrix} = -2-3 = -5 \)…
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