RREF of $$$\left[\begin{array}{cccc}- \sqrt{6} & 0 & 1 & 0\\0 & - \sqrt{6} & 1 & 0\\1 & 1 & - \sqrt{6} & 2\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Find the reduced row echelon form of $$$\left[\begin{array}{cccc}- \sqrt{6} & 0 & 1 & 0\\0 & - \sqrt{6} & 1 & 0\\1 & 1 & - \sqrt{6} & 2\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$.

Divide row $$$1$$$ by $$$- \sqrt{6}$$$: $$$R_{1} = - \frac{\sqrt{6}}{6} R_{1}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & - \frac{\sqrt{6}}{6} & 0\\0 & - \sqrt{6} & 1 & 0\\1 & 1 & - \sqrt{6} & 2\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Subtract row $$$1$$$ from row $$$3$$$: $$$R_{3} = R_{3} - R_{1}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & - \frac{\sqrt{6}}{6} & 0\\0 & - \sqrt{6} & 1 & 0\\0 & 1 & - \frac{5 \sqrt{6}}{6} & 2\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Divide row $$$2$$$ by $$$- \sqrt{6}$$$: $$$R_{2} = - \frac{\sqrt{6}}{6} R_{2}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & - \frac{\sqrt{6}}{6} & 0\\0 & 1 & - \frac{\sqrt{6}}{6} & 0\\0 & 1 & - \frac{5 \sqrt{6}}{6} & 2\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Subtract row $$$2$$$ from row $$$3$$$: $$$R_{3} = R_{3} - R_{2}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & - \frac{\sqrt{6}}{6} & 0\\0 & 1 & - \frac{\sqrt{6}}{6} & 0\\0 & 0 & - \frac{2 \sqrt{6}}{3} & 2\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Multiply row $$$3$$$ by $$$- \frac{\sqrt{6}}{4}$$$: $$$R_{3} = - \frac{\sqrt{6}}{4} R_{3}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & - \frac{\sqrt{6}}{6} & 0\\0 & 1 & - \frac{\sqrt{6}}{6} & 0\\0 & 0 & 1 & - \frac{\sqrt{6}}{2}\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Add row $$$3$$$ multiplied by $$$\frac{\sqrt{6}}{6}$$$ to row $$$1$$$: $$$R_{1} = R_{1} + \frac{\sqrt{6}}{6} R_{3}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & 0 & - \frac{1}{2}\\0 & 1 & - \frac{\sqrt{6}}{6} & 0\\0 & 0 & 1 & - \frac{\sqrt{6}}{2}\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Add row $$$3$$$ multiplied by $$$\frac{\sqrt{6}}{6}$$$ to row $$$2$$$: $$$R_{2} = R_{2} + \frac{\sqrt{6}}{6} R_{3}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & 0 & - \frac{1}{2}\\0 & 1 & 0 & - \frac{1}{2}\\0 & 0 & 1 & - \frac{\sqrt{6}}{2}\\0 & 0 & 2 & - \sqrt{6}\end{array}\right]$$$

Subtract row $$$3$$$ multiplied by $$$2$$$ from row $$$4$$$: $$$R_{4} = R_{4} - 2 R_{3}$$$.

$$$\left[\begin{array}{cccc}1 & 0 & 0 & - \frac{1}{2}\\0 & 1 & 0 & - \frac{1}{2}\\0 & 0 & 1 & - \frac{\sqrt{6}}{2}\\0 & 0 & 0 & 0\end{array}\right]$$$

Since the element at row $$$4$$$ and column $$$4$$$ (pivot element) equals $$$0$$$, we need to swap the rows.

Find the first nonzero element in column $$$4$$$ under the pivot entry.

As can be seen, there are no such entries.

The reduced row echelon form is $$$\left[\begin{array}{cccc}1 & 0 & 0 & - \frac{1}{2}\\0 & 1 & 0 & - \frac{1}{2}\\0 & 0 & 1 & - \frac{\sqrt{6}}{2}\\0 & 0 & 0 & 0\end{array}\right]\approx \left[\begin{array}{cccc}1 & 0 & 0 & -0.5\\0 & 1 & 0 & -0.5\\0 & 0 & 1 & -1.224744871391589\\0 & 0 & 0 & 0\end{array}\right].$$$A