In algebra, we represent an unknown number using variables. We use letters to denote these variables.

A variable is a symbol that can be used to represent one or more numbers. A variable is any symbol that may be replaced by numbers. It is a letter used to represent an arbitrary element of a set called as a variable.

For example, consider the equation 2x + 3y = 10. Here, x and y are known as variables.

Example:

Solve 2x + x

Solution:

2x + x

Here, we observe that the variables are similar i.e. 2x, x. So, we need to add the variables.

2x + x = 3x

An unknown value in an algebraic expression is known as a variable. These variables are denoted by letters.

For example, let the cost of a pen be x dollar, then the cost of 2 pens will be x + x = 2x dollars. Here, we do not know the exact value of x, if we put the value of x = 2, then the cost of 2 pens is 4 dollars. If we put the value of x = 3, then the cost of 2 pens is 6 dollars. So, we observe that we can put any values in place of x. Here, x is known as a variable.