Definition of Constant:
As the name implies constant is a value that remains constant ever. Constant has a fixed value and its value cannot be changed by any variable. Constants are represented by numbers.
For example in the algebraic expression
3x + 5y = 7, where 7 is the constant we know its face value is 7 and it cannot be changed. But 3x and 5y are not constants because the variable x and y can change their value.
Definition of Variable:
A value that keeps on changing is said to be variable. Variables are often represented by an alphabet like a, b, c or x, y, z. Its value changes from time to time.
For example in the algebraic expression:
3x + 5y = 7 where x and y are variables that are changed according to the expression.
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Difference Between Constant and Variables
Below is the tabular format of the difference between variable and constant. It will make you more clear what is variable and constant.
Difference between Variable and Constant
From the above table now you have a clear picture of what is the difference in constant and variable.
Now let us solve some examples which will make it more clear what is variable and constant.
Example 1 :
Find the value of x for the equation x – 4 = 0
x – 4 = 0
Add 4 to each side.
X – 4 + 4 = 4
x = 4
So, the value of x is 4.
Example 2 :
Find the value of x for the equation 3x = 27
3x = 27
Divide each side by 3.
3x/3 = 27/3
x = 9
So, the value of x is 9.
Example 3 :
Find the value of x for the equation x + 5 = -2
x + 5 = -2
Subtract 5 from each side.
x + 5 – 5 = -2 -5
x = -7
So, the value of x is -7.
Example 4 :
Find the value of x for equation 4x + 6 = 22.
4x + 6 = 22
Subtract 6 from each side.
4x + 6 – 6 = 22 – 6
4x = 16
Divide each side by 4.
4x/4 = 16/4
x = 4
So, the value of x is 4
So from these problems, we have got different values for the same alphabet x.the values of x keeps on changing depending upon the equation,
So alphabet x is said to be variable.
Find the value of x for the following equation
5x + 10 = 15
7x + 7 = 28
x + 15 = 20
x – 8 = 2