The lecture notes for linear algebra by Gilbert Strang can be downloaded from the MIT OpenCourseWare website. The notes are available in PDF format and can be accessed at:
The single best place to find is directly from MIT OpenCourseWare . The official 18.06 course page contains a treasure trove: lecture notes for linear algebra gilbert strang pdf
: The most comprehensive source for official notes. You can find 18.06 Lecture Notes organized by unit, covering topics from matrix elimination to singular value decomposition. The lecture notes for linear algebra by Gilbert
Here are some tips for using the lecture notes for linear algebra by Gilbert Strang: lecture notes for linear algebra gilbert strang pdf
How elimination is actually matrix multiplication. Vector Spaces and Subspaces: The "heart" of the course.