a) |x–3|=11
⇒$\left \{ {{x-3=11} \atop {x-3=-11}} \right.$
⇒$\left \{ {{x=11+3} \atop {x=-11+3}} \right.$
⇒$\left \{ {{x=14} \atop {x=-8}} \right.$
Vậy x=14 hoặc x=-8
b) |x–1|–8=–4
|x-1| =-4 +8
|x–1| = 4
⇒$\left \{ {{x-1=4} \atop {x-1=-4}} \right.$
⇒$\left \{ {{x=4+1} \atop {x=-4+1}} \right.$
⇒$\left \{ {{x=5} \atop {x=-3}} \right.$
Vậy x=5 hoặc x=-3
