2(4-x)<-9x,8-2x<-9x9x-2x<-87x<-8x<-8/7|-x-1|-2|3x+2| =-x-1-2(-3x-2)=-x-1+6x+4=5x+3
2(4-x)<-9x8-2x<-9x7x<-8所以x<-8/7所以|-x-1|-2|3x+2| =-x-1-2*(-3x-2)=-x-1+6x+4=3+5x