I am trying to fully understand this theorem Theorem: Let A be an m x n matrix. The following are all true or all false. 1. For each b in Rm, the equation Ax has a solution 2. Each b in Rm is a linear combination of the columns of A. 3. The columns of A span Rm 4. A has a pivot position in every row. So when A does not have a pivot in every row, it disproves (1) because each b will not have a solution. How would you disprove (2) with (4)?