I've attached the question and solution as the answers. The problem I dont understand is number 12.

I assume the question is asking us to find Ax...In which case I got all of them wrong anyway

$\displaystyle \begin{bmatrix} 0 & 0 & 1 \\0 & 1 & 0 \\ 1 & 0 & 0 \\ \end{bmatrix} * \begin{bmatrix}x \\y \\z \\ \end{bmatrix} $

Using the row form, I simply dotted each row of the matrix by vector x. I ended up with the matrix (z y x)... the solution doesnt even have the answers as variables, they have numbers which I dont understand.

For the second one I got (0 0 0), but the answers say (0 0)... how is this even possible? How can there only be 2 dimensions to that vector?

For the third one, I got (3 3 6), which is also wrong compared to the back of the book. For all of them I did it using the row multiplication (dot products).

I think I am misunderstanding the problem.