Introduction To Unknown

 

Try to solve the missing number question given below. Since the numbers are easy, we can guess them right

-----

2

=

4

Answer : 6 − 2 = 4.

But in algebra we use an alphabet. Therefore we can rewrite the above equation as

x

2

=

4

Since we do not know the value of the variable until it is solved, it is called the unknown or the variable.

And when we solve it we write:

x

=

6

Demonstration:

Solve this one:

x

+

5

=

12

Let us  subtract 5 from both sides:

x + 5 −5 = 12 −5

 (5−5 = 0 and 12−5 = 7)

Therefore,   x + 0 = 7

i.e.,  x = 7