Ответ:

[tex]\left \{ {{-x\geq 3-2} \atop {3x\leq 2+1}} \right. \\\left \{ {{-x\geq 1} \atop {3x\leq 3}} \right. \\\left \{ {{x\geq -1} \atop {x\leq 1}} \right.[/tex]

x∈[-1:1]