Solve the system \left\{ \begin{array}{[email protected]{}[e mail protected]{}[email protected]{ }[email protected]{}[email protecte d]{}r} 5 x_1 & - 6 x_2 & + 3 x_3 & + 2 x_4 = & 2 \cr - x_1 & + x_2 & + 2 x_3 & + 2 x_4 = & 3 \cr 4 x_1 & - 5 x_2 & + 5 x_3 & + 4 x_4 = & 5 \cr -2 x_1 & + 2 x_2 & + 4 x_3 & + 4 x_4 = & 6 \end{array} \right. \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right[ x_1 \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right] x_2 x_3 x_4 = \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right[ \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right] + \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right[ \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right] s + \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right[ \left.\vphantom{\begin{array}{c}\!\ strut\\\!\strut\\\!\strut\\\!\strut \\\!\strut\\\end{array}}\right] t.