If $A=\begin{bmatrix}a & 0 & 0 \\0 & a & 0\\ 0 & 0 & a\end{bmatrix}, a≠ 0$ then |adj A| is equal to
Answer & explanation
Correct answer: option 3
$A=\begin{bmatrix}a & 0 & 0 \\0 & a & 0\\ 0 & 0 & a\end{bmatrix}$ so $|A|=a^3$
so $A\,adj\,A=|A|I_3$
so $|A||adj\,A|=|A|^3$
$|adj\,A|=|A|^2=(a^3)^2=a^6$