Linearization of a System of Differential Equations

Linearization is the process of making a nonlinear system of differential equations linear. We essentially find the jacobian matrix of our nonlinear system. Given a nonlinear system in the form:

We can create a first order linear system in the form of:

A two-dimensional autonomous system is called an almost linear system at an equilibrium point if -- see page 437 of diffeq textbook