Variable

Is a symbol for a number we don’t know yet. X is the variable in the term 4X.

The “letters” in an equation are the variables.

The variable nature of letters' sizes makes them very difficult to manage.

Example 1

`a^2+9^2=100` 

In the above equation “a” is the variable.

Example 2

`a^2+b^2=c^2` 

In the above equation a, b and c are all variables.

Example 3

`136=\pir^2` 

In the above equation r is the variable.