Determine the value(s) of $x$ such that

$\left[\begin{array}{ccc} x &2 &1\cr \end{array}\right] \left[\begin{array}{ccc} 1 &4 &-1\cr 4 &2 &3\cr -1 &-50 &0 \end{array}\right] \left[\begin{array}{c} x\cr -1\cr -5\cr \end{array}\right] = [0]$

$x$ =
Note: If there is more than one value separate them by commas.