If A = $\begin{bmatrix$}[r] 5 & -2 \ 7 & 0 \end{bmatrix} \text{ and B} = \begin{bmatrix}[r] 8 \ 3 \end{bmatrix}, then which of the following is not possible ?

1. A²

2. AB

3. BA

4. 15A

If A = $\begin{bmatrix$}[r] 1 & 0 \ 1 & 1 \end{bmatrix}, B = \begin{bmatrix}[r] 0 & 1 \ 1 & 0 \end{bmatrix}\text{ and C} = \begin{bmatrix}[r] 1 & 1 \ 0 & 0 \end{bmatrix}, the matrix A² + 2B - 3C is :

1. $\begin{bmatrix$}[r] -2 & -1 \ 4 & 1 \end{bmatrix}

2. $\begin{bmatrix$}[r] 2 & -1 \ 4 & 1 \end{bmatrix}

3. $\begin{bmatrix$}[r] 2 & 1 \ 4 & 1 \end{bmatrix}

4. $\begin{bmatrix$}[r] 2 & 1 \ -4 & -1 \end{bmatrix}

Evaluate : if possible :

$\begin{bmatrix$}[r] 1 & -2 \ \end{bmatrix}\begin{bmatrix}[r] -2 & 3 \ -1 & 4 \end{bmatrix}

Evaluate : if possible :

$\begin{bmatrix$}[r] 6 & 4 \ 3 & -1 \end{bmatrix}\begin{bmatrix}[r] -1 \ 3 \end{bmatrix}