Matrix A has dimensions 5 x 1. Matrix B has dimensions 5 x 1. These two matrices can be multiplied.
No, this is incorrect. The number of columns of the first matrix has to equal the number of rows of the second matrix so that the matrices would be able to be multiplied. This is not the case here because the number of columns of the second matrix is 1 and the number of rows of the second matrix is 5.