Topics on Test 3:
+ Subspaces of Rn (Sections 2.8 and 4.2 of Lay)
+ Nul(A), Col(A) and their Bases (Sections 2.8 and 4.2 of Lay)
+ Dimension and Rank  (Sections 2.9 of Lay)
+ Relative Bases (Sections 2.9, 4.3 and 4.4 of Lay)
+ The matrix of a Linear Transformation (Sections 1.8 and 1.9 of Lay)
+ Invertibility of Matrices (Section 2.3 of Lay and the handout on Openlab)
+ The inverse of a Matrix (Section 2.2 of Lay)

Extra credit
+ Compute the left inverse of a "tall" matrix of maximum rank. Here "tall" means more rows than columns. (See the handout on Openlab)