JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant
Let for \(A=\left[\begin{array}{lll}1 & 2 & 3 \\ a & 3 & 1 \\ 1 & 1 & 2\end{array}\right],|A|=2\). If \(|2 \operatorname{adj}(2 \operatorname{adj}(2 A ))|\) \(=32^{ n }\), then \(3 n +\alpha\) is equal to
- A \(10\)
- B \(9\)
- C \(12\)
- D \(11\)
Answer & Solution
Correct Answer
(D) \(11\)
Step-by-step Solution
Detailed explanation
\(A=\left[\begin{array}{lll}1 & 2 & 3 \\ a & 3 & 1 \\ 1 & 1 & 2\end{array}\right] \quad| A |=2\) \(1(6-1)-2(2 \alpha-1)+3(\alpha-3)=2\) \(5-4 \alpha+2+3 \alpha-9=2\) \(-\alpha-4=0\) \(\alpha=-4\) \(8|\operatorname{Adj}(2 \operatorname{Adj}(2 A ))|\)…
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