This text introduces the methods of applied functional analysis and applied convexity. Suitable for advanced undergraduates and graduate students of mathematics, science, and technology, it focuses on the solutions to two closely related problems. The first concerns finding roots of systems of equations and operative equations in a given region. The second involves extremal problems of minimizing or maximizing functions defined on subsets of finite and infinite dimensional spaces. Rather than citing practical algorithms for solving problems, this treatment provides the tools for studying problem-related algorithms. Topics include iterations and fixed points, metric spaces, nonlinear programming, polyhedral convex programming, and infinite convex programming. Additional subjects include linear spaces and convex sets and applications to integral equations. Students should be familiar with advanced calculus and linear algebra. As an introduction to elementary functional analysis motivated by application, this volume also constitutes a helpful reference for theoretically minded engineers, scientists, and applied mathematicians.