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

ધારો કે \(\alpha \beta \neq 0\) અને \(\mathrm{A}=\left[\begin{array}{rrr}\beta & \alpha & 3 \\ \alpha & \alpha & \beta \\ -\beta & \alpha & 2 \alpha\end{array}\right]\). જો \(B=\left[\begin{array}{rrr}3 \alpha & -9 & 3 \alpha \\ -\alpha & 7 & -2 \alpha \\ -2 \alpha & 5 & -2 \beta\end{array}\right]\) એ \(A\) ના ઘટકોના સહઅવયવો નો શ્રેણિક હોય, તો \(\operatorname{det}(A B) =\) ............

  1. A \(343\)
  2. B \(125\)
  3. C \(64\)
  4. D \(216\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(216\)

Step-by-step Solution

Detailed explanation

Equating co-factor fo \(\mathrm{A}_{21}\) \( \left(2 \alpha^2-3 \alpha\right)=\alpha \) \( \alpha=0,2 \text { (accept) }\) Now, \(2 \alpha^2-\alpha \beta=3 \alpha\) \( \alpha=2 \quad \beta=1 \) \( |A B|=|A \operatorname{cof}(A)|=|A|^3\)…
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