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| Classification of Differential Equation |
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| Differential equation are classified according to their order. |
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| The differential equation in which only the first derivative of the unknown function appears, is called First order differential equation. |
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| Example: |
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| Differential equations of order 2 or more are known as Higher order differential equation. |
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| Example: |
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| is a higher order differential equation. |
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| Differential equations are also classified according to their linearity and non- linearity. |
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| A differential equation is said to be linear, if the unknown function and its derivatives occur only in the first degree and are not multiplied together. |
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| Example: |
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| Note that the degree of a linear differential equation is 1, but a differential equation whose degree is 1, need not be linear. |
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| Example: |
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| is a differential equation of degree 1, but it is not linear because the unknown function y and its derivative are multiplied together. |
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| A differential equation which is not linear, is called non-linear. |
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| Example: |
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is a non - linear differential equation because  is multiplied by itself. |
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