The path
Vectors → pictures of Ax = b → projection → least squares → maps, eigen, SVD.
Lessons 1–14 are ready. The course stops here.
Ready
Vectors
A list is also an arrow. Add two, and the tip is a real point.
Ready
Pictures of Ax = b
Those arrows become columns, then two lines. Elimination, the inverse, and the nullspace solve the same A.
Ready
Projection
The closest point in C(A) is a drop-perpendicular. When b is not in the columns you kept, that leftover is the fit.
Ready
Maps, eigen, SVD
The same product as a map of the plane. Then the arrows that only stretch. Then the circle that becomes an ellipse. Then those three maps multiply.