Note Set 11a: Why Column Space and Nullspace are Subspaces—And Inigo

We introduce Inigo, a new matrix to befriend. We show in general that Column Space and Nullspace are both good subspaces because they are both made up all linear superpositions of specific sets of vectors. We finish with the concept of spanning sets of vectors, setting the stage for bases and dimensions.
Best consumed by 2016/10/05