Show that the equation $Ax=b$ is not consistent for all possible $b$, and describe the set of all $b$ for which the equation is consistent, both algebraically and geometrically.
$A = \begin{bmatrix} 1& 3& -4\\ -2& 1& 2\\ 3 &2& -6 \end{bmatrix}$
$b = \begin{bmatrix}b_1\\b_2\\b_3\end{bmatrix}$