Linear Algebra and Its Applications (5th Edition)

$\begin{bmatrix}\blacksquare&*\\0&\blacksquare\\0&0\end{bmatrix}$ $\begin{bmatrix}\blacksquare&*\\0&0\\0&0\end{bmatrix}$ $\begin{bmatrix}0&\blacksquare\\0&0\\0&0\end{bmatrix}$