Q61 / 155 · WBJEE 2016 · Mathematics

Let $A$ be a $3 \times 3$ matrix and $B$ be its adjoint matrix. If $|B|=64,$ then $|A|$ is equal to

  • A
    ±2
  • B
    $\pm 4$
  • Correct answer
    C
    $\pm 8$
  • D
    ±12

Solution

We have, $|B|=64$ $\Rightarrow |\operatorname{adj} A \mid=64$ $\Rightarrow|A|^{2}=64$ $|A|=\pm 8$

Hence, the correct answer is option: 'C'.

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