The matrix, A = $\begin{bmatrix} 4 & 0 & 0 \ 0 & 3 & 0 \ 0 & 0 & -7 \end{bmatrix}$ is a:

1. Rectangular matrix

2. Column matrix

3. Diagonal matrix

4. Identity matrix

A matrix of order of 3 × 1 whose elements a_ij are given by a_ij = (2i + j), is :

1. $\begin{bmatrix} 3 & 5 & 7 \end{bmatrix}$

2. $\begin{bmatrix} 3 \ 5 \ 7 \end{bmatrix}$

3. $\begin{bmatrix} 2 & 4 & 6 \end{bmatrix}$

4. $\begin{bmatrix} 2 \ 4 \ 6 \end{bmatrix}$

If a matrix has 12 elements, then the total number of possible orders it can have is:

1. 4

2. 6

3. 8

4. cannot be determined

A 2 × 2 matrix whose elements are given by a_ij = $\dfrac{(i + 2j)^2}{2}$ is:

1. $\begin{bmatrix} \dfrac{3}{2} & \dfrac{5}{2} \ \space & \space \ 8 & 18 \end{bmatrix}$

2. $\begin{bmatrix} \dfrac{5}{2} & \dfrac{7}{2} \ \space & \space \ 8 & 18 \end{bmatrix}$

3. $\begin{bmatrix} \dfrac{9}{2} & \dfrac{15}{2} \ \space & \space \ 8 & 18 \end{bmatrix}$

4. $\begin{bmatrix} \dfrac{9}{2} & \dfrac{25}{2} \ \space & \space \ 8 & 18 \end{bmatrix}$