1. (Addition of matrices)
\[
\text { If } A=\left(\begin{array}{ccc}
-4 & 6 & 3 \\
0 & 1 & 2
\end{array}\right) \quad A=\left(\begin{array}{ccc}
5 & -1 & 0 \\
3 & 1 & 0
\end{array}\right)
\]

Step 1 ：Given two matrices A and B as follows:

Step 2 ：\[ A = \left(\begin{array}{ccc} -4 & 6 & 3 \\ 0 & 1 & 2 \end{array}\right) \]

Step 3 ：\[ B = \left(\begin{array}{ccc} 5 & -1 & 0 \\ 3 & 1 & 0 \end{array}\right) \]

Step 4 ：The addition of two matrices is performed element-wise, meaning that each element in the first matrix is added to the corresponding element in the second matrix.

Step 5 ：Performing the addition, we get the matrix C as follows:

Step 6 ：\[ C = \left(\begin{array}{ccc} 1 & 5 & 3 \\ 3 & 2 & 2 \end{array}\right) \]

Step 7 ：Final Answer: The sum of the two matrices A and B is

Step 8 ：\[\boxed{\begin{array}{ccc} 1 & 5 & 3 \\ 3 & 2 & 2 \end{array}}\]