For any 2 × 2 matrix A, if $A (adj\, A) =\begin{bmatrix}10&0\\0&10\end{bmatrix}$, then $|A|$ is equal to
Answer & explanation
Correct answer: option 3
We know that for any square matrix A.
$A (adj\, A) = |A|I$
$∴A (adj\, A) =\begin{bmatrix}10&0\\0&10\end{bmatrix}=10I_2⇒|A|I_2=10I_2⇒|A|=10$