Answer
The required value of the array is $\left[ \begin{matrix}
1 & 2 & -1 \\
0 & -11 & -11 \\
\end{matrix} \right]$
Work Step by Step
The given array is:
$\left[ \begin{matrix}
1 & 2 & -1 \\
4 & -3 & -15 \\
\end{matrix} \right]$ (I)
Then multiply row 1st of equation (I) by $-4$ and then add this to the 2nd row numbers by using the relation:
${{R}_{2}}\to {{R}_{1}}\times \left( -4 \right)+{{R}_{2}}$
After that,
$\left[ \begin{matrix}
1 & 2 & -1 \\
1\left( -4 \right)+4 & 2\left( -4 \right)+\left( -3 \right) & -1\left( -4 \right)+\left( -15 \right) \\
\end{matrix} \right]$
Thus,
$\left[ \begin{matrix}
1 & 2 & -1 \\
0 & -11 & -11 \\
\end{matrix} \right]$
Hence, the required array is: $\left[ \begin{matrix}
1 & 2 & -1 \\
0 & -11 & -11 \\
\end{matrix} \right]$.
