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CUET · MATHS · PYQ PAPER 2025

Let \(A=\left[\begin{array}{ccc}1 & 2 & 1 \\ -1 & 3 & 2 \\ 2 & 4 & 1\end{array}\right]\) and \(M_{i j}, A_{i j}\) respectively denote the minor, co-factor of an element \(a_{i j}\) of matrix \(A\), then which of the following are true?
(A) \(M_{22}=-1\)
(B) \(A_{23}=0\)
(C) \(A_{32}=3\)
(D) \(M_{23}=1\)
(E) \(M_{32}=-3\)
Choose the correct answer from the options given below:

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

Answer & Solution

Correct Answer

(A) (A) and (B) only

Step-by-step Solution

Detailed explanation

\(M_{22} = \det\left[\begin{array}{cc}1 & 1 \\ 2 & 1\end{array}\right] = 1 - 2 = -1\) Therefore, (A) is true. \(M_{23} = \det\left[\begin{array}{cc}1 & 2 \\ 2 & 4\end{array}\right] = 4 - 4 = 0\) \(A_{23} = (-1)^{2+3} M_{23} = - (0) = 0\) Therefore, (B) is true.…
From CUET
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