If $I$ is a unit matrix,then $3I$ will be

For matrix $A = \begin{bmatrix} 2 & 3 \\ 4 & 5 \end{bmatrix}$, if $A^2 - 2I = KA$, then $K = \dots$

If $A=\left[\begin{array}{ccc}1 & -2 & 1 \\ 2 & 1 & 3\end{array}\right]$ and $B=\left[\begin{array}{cc}2 & 1 \\ 3 & 2 \\ 1 & 1\end{array}\right]$,then $(AB)^{\prime}$ is equal to

If $A$ and $B$ are two matrices such that $A+B$ and $AB$ are both defined,then

The matrix $A = \frac{1}{3}\begin{bmatrix} 1 & 2 & 2 \\ 2 & 1 & -2 \\ -2 & 2 & -1 \end{bmatrix}$ is

If $A = \begin{bmatrix} i & 1 \\ 0 & i \end{bmatrix}$,then $A^4$ equals