The answer to part a) is
( 1 0 − 3 1 − 2 − 2 1 1 1 ) ( x 1 x 2 x 3 ) = ( 0 0 0.25 ) {\displaystyle {\begin{pmatrix}1&0&-3\\1&-2&-2\\1&1&1\end{pmatrix}}{\begin{pmatrix}x_{1}\\x_{2}\\x_{3}\end{pmatrix}}={\begin{pmatrix}0\\0\\0.25\end{pmatrix}}}
In augmented matrix form, this becomes
( 1 0 − 3 | 0 1 − 2 − 2 | 0 1 1 1 | 0.25 ) {\displaystyle \color {blue}{\begin{pmatrix}1&0&-3&|&0\\1&-2&-2&|&0\\1&1&1&|&0.25\end{pmatrix}}}
