**By a differential equation we mean an equation involving independent variable , dependent variable and the differential coefficients of the dependent variable i.e. it will be an equation in x, y and derivatives of y w .r .t x. e.g.**

**Order and Degree of a Differential Equation:**

**Order and Degree of a Differential Equation:**

**The order of the highest differential coefficient appearing in the differential equation is called the order of the differential equation ,**

**while the exponent of the highest differential coefficient , when the differential equation is a polynomial in all the differential coefficients, is known as the degree of the differential equation.**

**Example : Find the order and degree (if defined) of the following differential equations:**

**(i) **

**(ii) **

**(iii) **

**Solution:**

**(i) The given differential equation can be re-written as **

**⇒ dy/dx = ln y . Hence its order is 1 and degree 1.**

**(ii) The given differential equation can be re-written as**

**Hence its order is 2 and degree 1.**

**(iii) Its order is 2. Since the given differential equation cannot be written as a polynomial in all the differential coefficients, the degree of the equation is not defined.**

**Exercise : **

**Find the order and the degree of the following differential equations**

**(i) **

**(ii) **

**(iii)**

**(iv) **