# Simple short question on differentials

#### idontknow

Does the equation below have an integrating factor? If not, why? If yes, why?
$$\displaystyle X''+p(x)X'+q(x)X=f(x)$$

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#### SDK

Answer is yes because it is a linear equation and every linear equation has a solution by integrating factor method. Sometimes this is called the variation of constants method when applied to higher order equations but they are exactly the same method.

#### mathman

Forum Staff
Integrating factors can be used in general for first order equations. For higher order some work will be required.