# Problems on Classification of Matrices

Here we will solve different types of Problems on classification of matrices

1. Let A = $$\begin{bmatrix} -5\\3\\ 2 \end{bmatrix}$$, B = $$\begin{bmatrix} 8 & 1\\ -6 & 7 \end{bmatrix}$$, C = $$\begin{bmatrix} 6 & 7 & -4\\ -1 & 1 & 2\\ 3 & 0 & 5 \end{bmatrix}$$,

X = $$\begin{bmatrix} 3 & 6\\ -2 & 7\\ 0 & 1 \end{bmatrix}$$, Y = $$\begin{bmatrix} 8 & 0 & -4 \end{bmatrix}$$.

Indicate the class of each of the matrices.

Solution:

A = $$\begin{bmatrix} -5\\3\\ 2 \end{bmatrix}$$

A is a column matrix, because it has exactly one column.

B = $$\begin{bmatrix} 8 & 1\\ -6 & 7 \end{bmatrix}$$

B is a square matrix, because number of rows = number of columns = 2

C = $$\begin{bmatrix} 6 & 7 & -4\\ -1 & 1 & 2\\ 3 & 0 & 5 \end{bmatrix}$$

C is a square matrix, because number of rows = number of columns = 3.

X = $$\begin{bmatrix} 3 & 6\\ -2 & 7\\ 0 & 1 \end{bmatrix}$$

X is a rectangular matrix, because number of rows ≠ number of columns.

Y = $$\begin{bmatrix} 8 & 0 & -4 \end{bmatrix}$$

Y is a row matrix, because it has exactly one row.

2. Construct a null matrix of the order 2 × 3 and a unit matrix of the order 3 × 3.

Solution:

A null matrix of the order 2 × 3 is $$\begin{bmatrix} 0 & 0 & 0\\ 0 & 0 & 0 \end{bmatrix}$$.

A unit matrix of the order 3 × 3 is $$\begin{bmatrix} 0 & 0 & 0\\ 0 & 0 & 0\\ 0 & 0 & 0 \end{bmatrix}$$.

Practice Problems on Classification of Matrices:

1. let A = [8     -7     5], B = $$\begin{bmatrix} 1 & -5\\ 3 & 7 \end{bmatrix}$$, C = $$\begin{bmatrix} 2 & 1 & 6\\ 1 & 0 & 5\\ 3 & 1 & 1 \end{bmatrix}$$, M = $$\begin{bmatrix} 1 & 0\\ 0 & 1 \end{bmatrix}$$ and N = $$\begin{bmatrix} 4 & -1\\ 2 & 0\\ 7 & -3 \end{bmatrix}$$.

(i) Identify the rectangular matrices.

(ii) Identify the square matrices.

(iii) Identify the row matrices and the column matrices.

(i) A and N are the rectangular matrices.

(ii) B, C and M are the square matrices.

(iii) A is the row matrix; and there is no column matrix.

2. (i) Constant the 2 × 3 zero matrix.

(ii) Constant the 4 × 4 unit matrix.

(i) 2 × 3 order zero matrix is $$\begin{bmatrix} 0 & 0 & 0\\ 0 & 0 & 0 \end{bmatrix}$$

(ii) 4 × 4 order unit matrix is $$\begin{bmatrix} 1 & 0 & 0 & 0\\ 0 & 1 & 0 & 0\\ 0 & 0 & 1 & 0\\ 0 & 0 & 0 & 1 \end{bmatrix}$$