b

(b A)^T = \( { \left(b × \begin{bmatrix} 1 & 2 \\ -1 & 3 \end{bmatrix} \right) }^{T} \)

= \( { \left(-2 × \begin{bmatrix} 1 & 2 \\ -1 & 3 \end{bmatrix} \right) }^{T} \)

= \( { \left(\begin{bmatrix} -2 × 1 & -2 ×2 \\ -2 ×-1 & -2 ×3 \end{bmatrix} \right) }^{T} = \begin{bmatrix} -2 & -4 \\ 2 & -6 \end{bmatrix}^{T}\)

= \(\begin{bmatrix} -2 & 2 \\ -4 & -6 \end{bmatrix}\)