If $A$ and $B$ are non-singular matrices,then which of the following is true?

If $A = \begin{bmatrix} 1 & 2 \\ 3 & 4 \end{bmatrix}$, then $\operatorname{Adj}(\operatorname{Adj}(\operatorname{Adj} A)) = $

Using elementary transformations,find the inverse of the following matrix,if it exists: $\left[\begin{array}{cc}1 & 2 \\ 2 & -1\end{array}\right]$

If $A=\begin{bmatrix} 4 & 5 \\ 2 & 1 \end{bmatrix}$ and $A^{2}-5A-6I=0$,then $A^{-1}=$

If $A=\left[\begin{array}{ccc}1 & -1 & 1 \\ 2 & 1 & -3 \\ 1 & 1 & 1\end{array}\right]$,$10 B=\left[\begin{array}{ccc}4 & 2 & 2 \\ -5 & 0 & \alpha \\ 1 & -2 & 3\end{array}\right]$ and $B$ is the inverse of $A$,then the value of $\alpha$ is

If $A=\begin{bmatrix} 3 & 0 & 0 \\ 0 & 5 & 0 \\ 0 & 0 & 4 \end{bmatrix}$ and $B=A^3$,then $B^{-1}=$