The Practically Cheating Calculus Handbook

A differential equation is an equation that involves an unknown function and its derivative. For example, the equation f’(x) + f(x) = x + 3 is a differential equation, with f(x) as the unknown function.

Ordinary differential equations are equations have a function as the solution rather than a number. In addition, differential equations contain information about the function’s derivatives. When solving differential equations, you may be required to solve an equation with an initial condition. For example, the differential equation ds⁄dt=cos(x) is an ordinary differential equation, butds⁄dt=cos(x);y(π) = 0 is an ordinary differential equation with an initial condition,