Question

I am looking at problem 6.3.10. I don't fully understand why A = [5 4][1 0] (or why defining it in such a manner is valid)

Answer 1

This should definately be: \[A = \left[5\ \ 4\right]^{T} * [1\ 0]\].
Multiplying yields \[A=\left[ \begin{smallmatrix}5&0\\ 4 &0 \end{smallmatrix} \right]\]