Step 1 :Given matrices A, B, C, D as follows:
Step 2 :\[A=\begin{bmatrix}1 & 2 & 3 \\ 2 & -1 & 1\end{bmatrix}\]
Step 3 :\[B=\begin{bmatrix}-2 & 0 & 1 \\ 3 & 0 & 1\end{bmatrix}\]
Step 4 :\[C=\begin{bmatrix}-1 \\ 2 \\ 4\end{bmatrix}\]
Step 5 :\[D=\begin{bmatrix}2 & 0 & 1\end{bmatrix}\]
Step 6 :For part a), we need to calculate the transpose of A and B and then add them. The transpose of a matrix is obtained by interchanging its rows into columns or columns into rows. So, we get:
Step 7 :\[A^{t}=\begin{bmatrix}1 & 2 \\ 2 & -1 \\ 3 & 1\end{bmatrix}\]
Step 8 :\[B^{t}=\begin{bmatrix}-2 & 3 \\ 0 & 0 \\ 1 & 1\end{bmatrix}\]
Step 9 :Adding these two matrices, we get:
Step 10 :\[A^{t}+B^{t}=\begin{bmatrix}-1 & 5 \\ 2 & -1 \\ 4 & 2\end{bmatrix}\]
Step 11 :For part b), we need to multiply matrix A by 2 and matrix B by 3 and then subtract the two resulting matrices. We get:
Step 12 :\[2A-3B=\begin{bmatrix}8 & 4 & 3 \\ -5 & -2 & -1\end{bmatrix}\]
Step 13 :For part c), we need to multiply matrix A with matrix C. Matrix multiplication is done element by element and then adding them up. We get:
Step 14 :\[A.C=\begin{bmatrix}15 \\ 0\end{bmatrix}\]
Step 15 :For part d), we need to multiply matrix C with matrix D. We get:
Step 16 :\[C.D=\begin{bmatrix}2\end{bmatrix}\]
Step 17 :So, the final answers are:
Step 18 :\[\boxed{A^{t}+B^{t}=\begin{bmatrix}-1 & 5 \\ 2 & -1 \\ 4 & 2\end{bmatrix}}\]
Step 19 :\[\boxed{2A-3B=\begin{bmatrix}8 & 4 & 3 \\ -5 & -2 & -1\end{bmatrix}}\]
Step 20 :\[\boxed{A.C=\begin{bmatrix}15 \\ 0\end{bmatrix}}\]
Step 21 :\[\boxed{C.D=\begin{bmatrix}2\end{bmatrix}}\]