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CUET · MATHS · PYQ PAPER 2025

If \(A=\left[\begin{array}{ll}5 & 6 \\ 3 & 2\end{array}\right]\), then which of the following is correct?
(A) \(|A|\) is positive
(B) \(|a d j A|=-8\)
(C) Cofactor of 3 is 6
(D) \(|2 A|=-32\)
Choose the correct answer from the options given below :

  1. A (B) and (D) only
  2. B (A), (B) and (C) only
  3. C (A), (C) and (D)
  4. D (C) and (D) only
Verified Solution

Answer & Solution

Correct Answer

(A) (B) and (D) only

Step-by-step Solution

Detailed explanation

\(|A| = (5)(2) - (6)(3) = 10 - 18 = -8\) Therefore, (A) \(|A|\) is positive is incorrect. \(adj A = \begin{bmatrix} 2 & -6 \\ -3 & 5 \end{bmatrix}\) \(|adj A| = (2)(5) - (-6)(-3) = 10 - 18 = -8\) Therefore, (B) \(|adj A| = -8\) is correct. Cofactor of 3 (\(C_{21}\))…