Find a non-zero vector $\vec{x}$ perpendicular to the vectors $$\vec{v}=\left[\begin{array}{c} -2\cr 9\cr 1 \end{array}\right] \ \mbox{ and } \ \vec{u}=\left[\begin{array}{c} -1\cr 4\cr -2 \end{array}\right].$$
$\vec{x}=$ $\left[\Rule{0pt}{3.6em}{0pt}\right.$$\left]\Rule{0pt}{3.6em}{0pt}\right.$