A^2=I - Vidyadip

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,
$|\text{A}^2|=|\text{I}|$
$\Rightarrow|\text{A}^2|=1$
$\Rightarrow|\text{A}|=\pm1$

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