-2 & 3 \\ 3 & 1 & 2 \\ 1 & 3 & -1 \end{array}\right) \cdot\left(\begin{array}{cccc} 4 & 0 & 0 & 5 \\ 1 & 7 & 2 & -5 \\ 3 & 0 & 0 & 0 \\ 8 & 3 & 1 & 7 \end{array}\right), \quad \text { and } \quad \cdot\left(\begin{array}{ccccc} n & n-1 & \cdots & 2 & 1 \\ 0-1 & n-2 & \cdots & 1 & 0 \\ \vdots & \vdots & \cdot & \vdots & \vdots \\ 2 & 1 & & 0 & 0 \\ 1 & 0 & \cdots & 0 & 0 \end{array}\right)

Fig: 1

Fig: 2