This textbook provides a practical understanding of how to apply differential equations in modern engineering and science. Incorporating valuable suggestions from mathematicians and mathematics professors, the second edition features an expanded chapter on classical solutions of ordinary linear differential equations, a full chapter on response of first- and second-order systems, new end-of-chapter problems, new exercises that can be used as projects, answers to many of the end-of-chapter problems, and new examples of applications related to chemical reactions, environmental engineering, biomedical engineering, and biotechnology.