If \(A'=\begin{bmatrix}3 & 5\\-6 & 5\end{bmatrix}\) and \(B=\begin{bmatrix}4 & 7\\-1 & 6\end{bmatrix}\) then (AB)' =
Answer & explanation
Correct answer: option 4
\((AB)'=B'.A'=\begin{bmatrix}4 & -1\\7 & 6\end{bmatrix}\begin{bmatrix}3 & 5\\-6 & 5\end{bmatrix}\)
\(\begin{bmatrix}12+6 & 20-5\\21-36 & 35+30\end{bmatrix}=\begin{bmatrix}18 & 15\\-15 & 65\end{bmatrix}\)