We can write the system in the following form:
[tex] \left[\begin{array}{cccc}5&-4&4&2\end{array}\right] \left[\begin{array}{c}x_1\\x_2\\x_3\\x_4\end{array}\right] =b[/tex]
The above system is equivalent to the following equation:
[tex]5x_1-4x_2+4x_3+2x_4=b,\forall b\in\mathbb{R}[/tex]
Of course, the above system has solution for any values of b since there is one equation and four variable, there is infinite number of solution each time.
