QuestionLet AA be a 3×53\times 5 matrix whose row echelon form is [12−1210013−2000k0],\begin{bmatrix}1&2&-1&2&1\\0&0&1&3&-2\\0&0&0&k&0\end{bmatrix}, where k∈Rk\in\mathbb{R}. Choose the correct option.
