CUET · MATHS · PYQ PAPER 2025
If \(c_{i j}\) denotes the cofactor of element \(c_{i j}\) of the matrix \(A=\left[\begin{array}{ccc}1 & 2 & -1 \\ 0 & -3 & 2 \\ 4 & 2 & 3\end{array}\right]\), then the value of \(c_{21} \cdot c_{33}\) is
- A -8
- B -3
- C -24
- D 24
Answer & Solution
Correct Answer
(D) 24
Step-by-step Solution
Detailed explanation
\(c_{21} = (-1)^{2+1} \det \left[\begin{array}{cc}2 & -1 \\ 2 & 3\end{array}\right] = -1 \cdot (6 - (-2)) = -8\) \(c_{33} = (-1)^{3+3} \det \left[\begin{array}{cc}1 & 2 \\ 0 & -3\end{array}\right] = 1 \cdot (-3 - 0) = -3\) \(c_{21} \cdot c_{33} = (-8) \cdot (-3) = 24\)
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