Question

If A is a square matrix of order 3 such that |A| = 3, then write the value of adj (adj A).

Answer 1

For any square matrix A, we have

$$\begin{gathered} \left|adj(adjA)\right|={\left|A\right|}^{{\left(n-1\right)}^2} \\ \Rightarrow \left|adj(adjA)\right|={\left(3\right)}^4=81 \end{gathered}$$