Question

If $A=\left[ 1\text{ }2\text{ }3 \right]$, then the set of elements of $A$ is
A) $\left\{ 1,2,3 \right\}$
B) $\left\{ 2,0 \right\}$
C) Only 2
D) None of these

Answer 1

Hint:
Here one matrix is given and we need to determine the set of elements of the given matrix. A matrix is defined as a collection of numbers which are arranged into a fixed number of columns and rows. The numbers which are used in a matrix are called as the elements of the matrix. So the elements of the given matrix will be the numbers used in the matrix.

Complete step by step solution:
Since $A=\left[ 1\text{ }2\text{ }3 \right]$ represents a matrix and we know the definition of matrix which is defined as a collection of numbers which are arranged into a fixed number of columns and rows.
We also know that the numbers which are used in a matrix are called as the elements of the matrix
We can see that only three numbers are used in the matrix, which are 1, 2 and 3.
Hence the elements of the given matrix are these three numbers which are used here in the matrix.
Therefore, elements of $A=\left\{ 1,2,3 \right\}$.

Hence, the correct option is option A.

Note:
We have obtained the elements of this matrix. A matrix is represented by the rectangular array containing elements which are arranged in rows and columns. We know that the numbers which are used in a matrix are called the elements of the matrix. Usually the numbers used in a matrix are real numbers but the elements of the matrix can also contain complex numbers. The number of elements in a matrix is equal to the product of number of rows in a matrix and the number of columns in a matrix.