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Class 12 Determinants · Assertion Reason1 Marksassertion_reason

Class 12 Maths · Determinants · Assertion Reason #25

Assertion: For A=\(\begin{bmatrix}1 & 1 & -2\\2 & 1 & -3\\5 & 4 & -9\end{bmatrix}\), C₂₂=1. Reason: The cofactor Cᵢⱼ equals (−1)ⁱ⁺ʲ times the minor Mᵢⱼ.

✅ Step-by-Step Solution

Final Answer: Option (A): Both A and R are true, and R correctly explains A.
  1. Deleting row 2 and column 2 leaves [[1,−2],[5,−9]], whose determinant is −9+10=1. The cofactor sign is positive.

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