Lecture
This lecture covers the operations involving triangular matrices, including the use of the QR factorization to solve linear systems. It explains how to calculate the solution of a system of linear equations using the QR factorization and the properties of triangular matrices. The lecture also demonstrates the process of finding the least squares solution for an overdetermined system. Additionally, it discusses the invertibility of matrices and the implications for solving linear systems. The instructor emphasizes the importance of understanding the properties of triangular matrices and their applications in solving linear algebra problems.