This lecture is part of the ICTP-SAIFR Minicourse on Partial Differential Equations: Analytical and Numerical Tools, delivered by Professor Oscar Reula from the National University of Córdoba, Argentina. Explore fundamental concepts of Linear Algebra in this nearly three-hour second class session, which builds upon previous material and prepares students for advanced topics in PDEs. The lecture is designed to strengthen mathematical foundations necessary for understanding both analytical approaches and numerical methods for solving partial differential equations. The complete minicourse runs from May 5 to June 30, 2025, offering comprehensive training in mathematical techniques essential for physics, engineering, and applied mathematics.