In this first volume you will find part of the introduction to Operations Research, where a first part of its history, definitions and various authors, theory, types of models, their applications, as well as the characteristics of a linear equation and its relationship with linear programming will be addressed. We will explore the development of several methods for the solution of a system of linear equations, such as the method of Addition and Subtraction, Substitution, Equalization, Cramer's Rule, Gaussian Elimination (Gauss-Jordan) and Upright, which will help to find the solution of two linear equations, which represent the intercept of these equations in the Graphical method, as well as the Simplex method for maximizing problems, and likewise the Double Phase method for minimizing problems, both methods for the development of mathematical models containing more than two variables. And finally an annex with a series of exercises as proposals to be solved.