Which one of the following is not true?

If $A = \begin{bmatrix} 1 & -2 \\ 3 & 0 \end{bmatrix}$,$B = \begin{bmatrix} -1 & 4 \\ 2 & 3 \end{bmatrix}$,$C = \begin{bmatrix} 0 & -1 \\ 1 & 0 \end{bmatrix}$,then $5A - 3B - 2C = $

If $A$ is a square matrix such that $A^2 = A$,then $(I + A)^3 - 8A =$ . . . . . . .

If $A = \begin{bmatrix} 1 & 0 \\ \frac{1}{2} & 1 \end{bmatrix}$,then $A^{50}$ is

If $m[-3, 4] + n[4, -3] = [10, -11]$, then $3m + 7n$ is equal to

$AB = 0$,if and only if