Answer
The sum is not defined.
Work Step by Step
1. Check if the matrices have the same dimension. If they don't, the sum/difference is not defined.
2. The sum/difference will be a matrix with the same dimension.
3. Position by position, add/subtract the corresponding entries.
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The dimensions do not match. One is a 1$\times$3 matrix, the other is 3$\times$1.
The sum is not defined.
