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Question: Answered & Verified by Expert
Let $A$ and $B$ be $(3 \times 3)$ matrices with $\operatorname{det} A=4$ and det $B=3$.
What is det $\left(3 \mathrm{AB}^{-1}\right)$ equal to ?
MathematicsDeterminantsNDANDA 2019 (Phase 1)
Options:
  • A 12
  • B 18
  • C 36
  • D 48
Solution:
2981 Upvotes Verified Answer
The correct answer is: 36
$\operatorname{det}\left(3 \mathrm{AB}^{-1}\right)=(3)^{3}|\mathrm{~A}|\left|\mathrm{B}^{-1}\right|$

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