Feedback on rank-thm

[Chris-Whaley]

In reference to version 224734d7be7ff0c4a8adb3a206356ea122112f33:

"The reader may have observed a relationship between the column space and the null space of a matrix. In this , the column space and the null space of a 3×2 matrix are both lines, in R2 and R3 respectively:"

The "R2" and "R3" should be interchanged. The column space is in R3, not R2. The null space is in R2, not R3.