Lecture Notes on Ordinary Differential Equations

The aim of this book is to make the study of differential equations enjoyable. Many standard texts use only the method of undetermined coefficients. These methods, however, are laborious and painstaking. In this book we introduce the elegant and powerful operator methods; we use them early and consistently. The student is also exposed to the undetermined coefficients method so that he/she can choose the appropriate method in a given situation. In the same vein, we illustrate the use of Leibniz's theorem to easily find the coefficients when one uses power series methods. Many applications are included, such as determination of orthogonal trajectories, envelopes, discussion of predator-prey and interspecies competition problems. There are ample exercises with answers and hints for solutions where necessary. This book has been extensively class tested.