Matrix Operations

4. Examples:

   1. $\begin{bmatrix}0 & -1 \\ 2 & 3\end{bmatrix} + \begin{bmatrix}4 & 1 \\ -2 & 5\end{bmatrix} = \begin{bmatrix}0 + 4 & -1 + 1 \\ 2 + (-2) & 3 + 5 \end{bmatrix} = \begin{bmatrix}4 & 0 \\ 0 & 8\end{bmatrix}$

   2. $\begin{bmatrix} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \\ 0 & 1 & 2 \end{bmatrix} + \begin{bmatrix} 9 & 8 & 7 \\ 6 & 5 & 4 \\ 3 & 2 & 1 \\ 2 & 1 & 0 \end{bmatrix} = \begin{bmatrix} 10 & 10 & 10 \\ 10 & 10 & 10 \\ 10 & 10 & 10 \\ 2 & 2 & 2 \end{bmatrix}$

   Fun Class Activity:
   1. Find two different non-zero matrices $A$ and $B$ such that $A + B = \textbf{0}$.
   2. What must be true about $A$ and $B$?