Hệ nào sau đây độc lập tuyến tính:

\[\left\{ {{{\rm{u}}_1} = (1,1,2);{{\rm{u}}_2} = (1, - 1, - 1),{{\rm{u}}_3} = (0,0,0)} \right\}\]

\[\left\{ {{{\rm{u}}_1} = ( - 2,1, - 1,1);{{\rm{u}}_2} = (1, - 1, - 1,2),{{\rm{u}}_3} = ( - 1,0, - 2,1)} \right\}\]

\[\left\{ {{{\rm{u}}_1} = ( - 2,1, - 1);{{\rm{u}}_2} = (1, - 1, - 1),{{\rm{u}}_3} = ( - 1,0, - 2)} \right\}\]

\[\left\{ {{{\rm{u}}_1} = (1,1);{{\rm{u}}_2} = (1, - 1)} \right\}\]