MCQ
$\text{A}^2=\text{I}\Rightarrow$
- A$|\text{A}|=0$
- B$|\text{A}|=1$
- C$|\text{A}|=-1$
- ✓$|\text{A}|=\pm1$
✓
Answer
Correct option: D.
$|\text{A}|=\pm1$
Given, $\text{A}^2=\text{I}$
Take determinant both sides,
$|\text{A}^2|=|\text{I}|\Rightarrow|\text{A}^2|=1\Rightarrow|\text{A}|=\pm1$
Take determinant both sides,
$|\text{A}^2|=|\text{I}|\Rightarrow|\text{A}^2|=1\Rightarrow|\text{A}|=\pm1$
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