**Linear equation** is the equation in which all the variables have exponent equal to 1. Lets take an example of linear equation . In this equation, we have just one variable and we can clearly notice that exponent of is 1. Similarly we can write few more examples of linear equations:

and

All the equations written above are linear equations in one variable but we can have multiple variables in linear equations.

For example, equation is a linear equation consisting of 2 variables.

Both of the variables ( and ) have exponent equal to 1.

In the same way, linear equation can also have more than 2 variables. For example, equation is a linear equation consisting of 3 variables.

Now lets try to write few equations which are not linear.

(Not linear because exponent of is not equal to 1)

(Not linear because exponent of is not equal to 1)

(Not linear because exponents of and respectively are not equal to 1)

**Practice:**

**Which of the following equation is linear?**

**(1)**

**(2)**

**(3)**

**(4)**

Clearly, the answer is** (2)** because it is the only equation in which both of the variables ( and ) have their exponents equal to 1.

**Which of the following equation is not linear?**

**(1)**

**(2)**

**(3)**

**(4)**

The answer is **(4)** because it is the only equation in which variable () has exponent which is not equal to 1.