Difference Between Constant and Variables

It is important to know the major differences between Constant and Variables before we learn about equations. These terms are used in majorly in algebra. Hence it very necessary for us to differentiate between the two.

Definition of Constant and Variables

Constant: A constant can simply be defined as a value used in mathematics for algebraic expressions and equations. A constant does not change over time and has a fixed value. For example, the size of a shoe or cloth or any apparel will not change at any point of time by itself.

In an algebraic expression, x+y = 8, 8 is a constant value and it cannot be changed.

Variables: Variables are the terms which can change or vary over time. It does not remain constant, unlike constant. For example, the height and weight of a person do not remain constant always and hence they are variables.

In an algebraic expression, x+y = 8, x and y are the variables and can be changed.

Let us figure out the other key differences between constants and variables.

What is the Difference between Constant and Variables?

These are primarily symbols that act as placeholders for a certain value. Variables are primarily represented in letters or phrases and do not have a fixed value attached to them. The value of a variable is unique and can change from one scenario to the other. Variables along with constants are used mainly in algebraic expressions. For a point by point difference between the two, check out the tabular column below:

Difference of Constants and Variables
Constant Variables
A constant does not change its value over time. A variable, on the other hand, changes its value dependent on the equation.
Constants are usually written in numbers. Variables are specially written in letters or symbols.
Constants usually represent known values in an equation, expression or in line of programming. Variables, on the other hand, represent unknown values.
Constants are used in computer programming. Variables also have its uses in computer programming and applications.

Solved Examples

1. What is the value of x in the given equation x+10=5

Solution: Given,

x+10 = 5

x = 5-10

x = -5

2. Find constant and variables  in the given expression.

(i) 3x = 9

(ii) x – y = -10


(i) In 3x = 9,

x is the variable and 9 is the constant.

If we further simplify the equation,

3x = 9

x = 9/3 = 3

then x is the variable and 3 is the constant.

(ii) x-y = -10

Here, x and y are the variables and -10 is the constant value.

Practice Questions on Difference Between Constant & Variables

Q.1: Find the value of x for the following equations:

(i) 2x+3 = 10

(ii) 10 x = 100

Q.2: Find the which are variables and which are constant for the following expressions.

(i) 3x+2 = 10

(ii) x+y = y + 9

Frequently Asked Questions – FAQs

What is the major difference between variables and constant?

The main difference between is variable is varying quantity and constant is a fixed value.

What are constants?Give an example

The constants are the value in an algebraic expression which cannot be changed. For example, in equation x+y=10, 10 is the constant value.

What are variables? Give an example

The variables are terms in an algebraic equation which can be changed or which are not fixed. For example, in equation x+y = 9, x and y are the variables.

What is an algebraic expression?

An expression or an equation which consist of variables, content, integers and mathematical operations is called algebraic expression.

Thus, these are some of the major differences between Constant and Variable. To know more about math related topics, download the BYJU’s app today!

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