If A is a square matrix of order 3 such that $|A|= 3$, then $|adj(adj\, A)|$ is equal to:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 81
Given: $A$ is a $3 \times 3$ matrix and $|A| = 3$.
For an $n \times n$ matrix:
$|\text{adj}\,A| = |A|^{\,n-1}$
Since $n = 3$:
$|\text{adj}\,A| = 3^{2} = 9$
Now apply the formula again to $\text{adj}\,A$ (which is also $3 \times 3$):
$|\text{adj}(\text{adj}\,A)| = |\text{adj}\,A|^{\,n-1}$
$= 9^{2}$
$= 81$
Thus, $|\text{adj}(\text{adj}\,A)| = 81$.