The general form of an ODE with order

is
As in the case of second-order ODEs, such an ODE can be classified as linear or nonlinear. The general form of a linear ODE of order

is
If

is the zero function, the equation is said to be
homogeneous. This discussion is primarily restricted to that case.
Many methods for solving linear second-order ODEs can be generalized to linear ODEs of order

, where

is greater than 2. If the order of the ODE is not important, it is simply called a linear ODE.