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JEE Mains · Maths · STD 12 - 3 and 4 . metrices and determinant

माना \(A =\left\{ a _{ ij }\right\}\) एक \(3 \times 3\) आव्यूह है, जबकि \(a_{i j}=\left\{\begin{aligned}(-1)^{j-i} & \text { if } i < j \\ 2 & \text { if } i=j \\(-1)^{i+j} & \text { if } i > j \end{aligned}\right.\) तो \(\operatorname{det}\left(3 Adj \left(2 A ^{-1}\right)\right)\) बराबर है....... |  

  1. A \(126\)
  2. B \(12\)
  3. C \(144\)
  4. D \(108\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(108\)

Step-by-step Solution

Detailed explanation

\(A=\left[\begin{array}{ccc}2 & -1 & 1 \\ -1 & 2 & -1 \\ 1 & -1 & 2\end{array}\right]\) \(|\mathrm{A}|=4\) \(\left|3 \operatorname{adj}\left(2 \mathrm{~A}^{-1}\right)\right|=\left|3 \cdot 2^{2} \operatorname{adj}\left(\mathrm{A}^{-1}\right)\right|\)…
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