A first-order ordinary differential equation (ODE) is an equation involving a function and its first derivative, representing the rate of change of the function in relation to the independent variable. Such equations are fundamental in modeling dynamic systems and can often be solved using techniques like separation of variables or integrating factors.
An exact differential equation is a type of differential equation that can be expressed in the form of a total differential of a function, implying that it has a potential function whose differential equals the given equation. Solving an exact differential equation involves finding this potential function, which is possible when the mixed partial derivatives of the terms are equal, indicating that the equation is exact.
Separable variables is a method used to solve differential equations where the variables can be separated on opposite sides of the equation, allowing the equation to be integrated with respect to each variable independently. This technique is particularly useful for first-order ordinary differential equations and is often one of the first methods taught in differential equations courses due to its simplicity and applicability.