Answer
$$\begin{bmatrix}
2&-1&\vdots &7\\ 1 & 1 &\vdots &2
\end{bmatrix}$$
Work Step by Step
In order to write a matrix that would solve this linear equation, we write the coefficients of each variable in their own column. Doing this, we find:
$$\begin{bmatrix}
2&-1&\vdots &7\\ 1 & 1 &\vdots &2
\end{bmatrix}$$
