Ответ:
2) (3; 6)
4) [2; +oo)
6) [0; +oo)
(oo - бесконечность)
Пошаговое объяснение:
2) 
3} \atop {x<6}} \right. \\3<x<6" alt="\left \{ {{x>3} \atop {x<6}} \right. \\3<x<6" align="absmiddle" class="latex-formula">
4) 
-1} \atop {x\geq 2}} \right. \\x\geq 2" alt="\left \{ {{x>-1} \atop {x\geq 2}} \right. \\x\geq 2" align="absmiddle" class="latex-formula">
6) 
-5}} \right. \\x\geq 0" alt="\left \{ {{x\geq 0} \atop {x>-5}} \right. \\x\geq 0" align="absmiddle" class="latex-formula">