Question
For what values of x: $\left[\begin{array}{lll}{1} & {2} & {1}\end{array}\right]$ $\left[\begin{array}{lll}{1} & {2} & {0} \\ {2} & {0} & {1} \\ {1} & {0} & {2}\end{array}\right]\left[\begin{array}{l}{0} \\ {2} \\ {x}\end{array}\right]$ = 0.