Solution
= Solution
Collect the coefficients of the three unknowns in rows. The <linear system> has <matrix> form
$$
\boxed{A\mathbf x=\mathbf b,\qquad
A=\begin{pmatrix}1&2&3\\1&-2&1\\2&1&-1\end{pmatrix},\quad
\mathbf x=\begin{pmatrix}x\\y\\z\end{pmatrix},\quad
\mathbf b=\begin{pmatrix}14\\0\\1\end{pmatrix}.}
$$
The next two parts solve this same system by the two requested methods.