Answer
$ \begin{bmatrix}
1&-1 &-5 \\
0 & -1 & -3 \\
\end{bmatrix}$
Work Step by Step
The augmented matrix is
$\begin{bmatrix}
1&-1 &-5 \\
-2 & 1 & 7 \\
\end{bmatrix}$
Perform the given operations.
$R_2\rightarrow R_2+2R_1$
$\Rightarrow \begin{bmatrix}
1&-1 &-5 \\
-2+2(1) & 1+2(-1) & 7+2(-5) \\
\end{bmatrix}$
Simplify.
$\Rightarrow \begin{bmatrix}
1&-1 &-5 \\
-2+2 & 1-2 & 7-10 \\
\end{bmatrix}$
$\Rightarrow \begin{bmatrix}
1&-1 &-5 \\
0 & -1 & -3 \\
\end{bmatrix}$
The above matrix is the upper triangular form.
