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

ધારોકે \(\alpha\) અને \(\beta\) વાસ્તવિક સંખ્યાઓ છે. \(3 \times 3\) શ્રેણિક \(A\) એવો છે કે જેથી \(A^2=3 A+\alpha I\). જો \(A^4=21 A+\beta I\) હોય, તો \(..........\)

  1. A \(\alpha=1\)
  2. B \(\alpha=4\)
  3. C \(\beta=8\)
  4. D \(\beta=-8\)
Verified Solution

Answer & Solution

Correct Answer

(D) \(\beta=-8\)

Step-by-step Solution

Detailed explanation

\(A ^2=3 A +\alpha I\) \(A ^3=3 A ^2+\alpha A\) \(A ^3=3(3 A +\alpha I )+\alpha A\) \(A ^3=9 A +\alpha A +3 \alpha I\) \(A ^4=(9+\alpha) A ^2+3 \alpha A\) \(=(9+\alpha)(3 A +\alpha I )+3 \alpha A\) \(= A (27+6 \alpha)+\alpha(9+\alpha)\)…
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