Edit: Minor edits in Sections WILA, SSLE, RREF, TSS

+Edit: Extended slightly the conclusion of Theorem HSC

<theorem acro="HSC" index="homogeneous system!consistent">

<title>Homogeneous Systems are Consistent</title>

-<p>Suppose that a system of linear equations is homogeneous. Then the system is consistent.</p>

+<p>Suppose that a system of linear equations is homogeneous. Then the system is consistent and one solution is found by setting each variable to zero.</p>

<li>Suppose a homogeneous system of equations has 13 variables and 8 equations. How many solutions will it have? Why?

-<li>Describe~~ in words (not symbols)~~ the null space of a matrix.

+<li>Describe, using only words, the null space of a matrix. (So in particular, do not use any symbols.)