Answer
$\left[\begin{array}{llll}
-1 & 1 & 2 & 0\\
0 & 4 & 7 & 4\\
1 & -2 & -1 & -1
\end{array}\right]$
Work Step by Step
$\left[\begin{array}{llll}
-1 & 1 & 2 & 0\\
3+3(-1) & 1+3(1) & 1+3(2) & 4+3(0)\\
1 & -2 & -1 & -1
\end{array}\right]$
$\left[\begin{array}{llll}
-1 & 1 & 2 & 0\\
0 & 4 & 7 & 4\\
1 & -2 & -1 & -1
\end{array}\right]$