Exercise 3.5.7

Invertible 3 by 3 matrix $A$ : row space basis $=$ column space basis $=(1,0,0),(0,1,0)$, $(0,0,1)$; nullspace basis and left nullspace basis are empty. Matrix $B=\left[\begin{array}{cc}A\hfill & A\hfill \end{array}\right]$: row space basis $(1,0,0,1,0,0),(0,1,0,0,1,0)$ and $(0,0,1,0,0,1)$; column space basis $(1,0,0),(0,1,0),(0,0,1)$; nullspace basis $(-1,0,0,1,0,0)$ and $(0,-1,0,0,1,0)$ and $(0,0,-1,0,0,1)$; left nullspace basis is empty.