#### Answer

$\left[\begin{array}{lllll}
3 & 2 & 0 & | & 5\\
-9 & 0 & 6 & | & 1\\
0 & -8 & 1 & | & 4
\end{array}\right]$

#### Work Step by Step

It is recommended to rewrite the system,
variable under variable (there are three):
$\begin{array}{llll}
3x & +2y & & =5\\
-9x & & 6z & =1\\
& -8y & +z & =4
\end{array}$
The missing terms have coefficients 0.
The augmented matrix of the system consists of
the elements of the coefficients matrix to the left,
and the elements of the constants matrix to the right
of (an optional) vertical line:
$\left[\begin{array}{lllll}
3 & 2 & 0 & | & 5\\
-9 & 0 & 6 & | & 1\\
0 & -8 & 1 & | & 4
\end{array}\right]$