Answer
$4B=\begin{bmatrix}
-12 & 4
\\
8 & -16
\\
-4 & 20
\end{bmatrix}$
Work Step by Step
Multiplying each element of $
B=
\begin{bmatrix}
-3 & 1
\\
2 & -4
\\
-1 & 5
\end{bmatrix}
$ by $4,$ then
\begin{align*}
4B&=
\begin{bmatrix}
-3(4) & 1(4)
\\
2(4) & -4(4)
\\
-1(4) & 5(4)
\end{bmatrix}
\\\\&=
\begin{bmatrix}
-12 & 4
\\
8 & -16
\\
-4 & 20
\end{bmatrix}
.\end{align*}
Hence, $
4B=\begin{bmatrix}
-12 & 4
\\
8 & -16
\\
-4 & 20
\end{bmatrix}
.$
