Differential Equations:

## F(t, y, dy/dt,....,d

^{n}y/dt^{n}) = 0;

## this is an n

^{th}order ordinary differential equation. The order of a differential equation is the difference between its highest and lowest orders within the equation (with y being a zero^{th }order derivative). Consider## dy/dt + y = 0; this is a first order differential equation.

## d

^{2}y/dt^{2 }+ dy/dt + y = 0; this is a second order.for compartmental kinetics example

A.9