Definition:First Order Ordinary Differential Equation

Definition
A first order ordinary differential equation is an ordinary differential equation in which any derivatives with respect to the independent variable have order no greater than $1$.

The general first order ODE can be written as:
 * $\map F {x, y, \dfrac {\d y} {\d x} }$

or, using prime notation:
 * $\map F {x, y, y'}$

If it is possible to do so, then it is often convenient to present such an equation in the form:
 * $\dfrac {\d y} {\d x} = \map f {x, y}$

that is:
 * $y' = \map f {x, y}$

It can also be seen presented in the form:
 * $\map \phi {x, y, y'} = 0$