0} \atop {6-3x<-21}} \right. \left \{ {{3x>-9} \atop {-3x<-27}} \right. " alt=" \left \{ {{9+3x>0} \atop {6-3x<-21}} \right. \left \{ {{3x>-9} \atop {-3x<-27}} \right. " align="absmiddle" class="latex-formula">
-3} \atop {x>9}} \right. " alt=" \left \{ {{x>-3} \atop {x>9}} \right. " align="absmiddle" class="latex-formula">
Ответ:3) x∈(9;+∞)