=>|3x+5|+|2x+3|+|x+1|=9x(1)
TH1: x<-5/3
(1) =>-3x-5-2x-3-x-1=9x
=>9x=-6x-9
=>15x=-9
=>x=-3/5(loại)
TH2: -5/3<=x<-3/2
(1) =>3x+5-2x-3-x-1=9x
=>9x=1
=>x=1/9(loại)
TH3: -3/2<=x<-1
(1): =>3x+5+2x+3-x-1=9x
=>9x=4x+7
=>5x=7
=>x=7/5(loại)
TH4: x>=-1
(1) =>3x+5+2x+3+x+1=9x
=>9x=6x+9
=>3x=9
=>x=3(nhận)