1.|x+3|= -|x|+3-2+3x
= |x+3|= -|x|+1+3x
= |x+3|+|x|-3x=1
+)TH1: x+3+x-3x=1, x+3≥0, x≥0
x=2, x+3≥0, x≥0
x=2, x≥-3, x≥0
+)TH2: -(x+3)+x-3x=1, x+3<0, x≥0
x=-4/3, x<-3, x≥0
+)TH3: x+3-x-3x=1, x+3≥0, x<0
x=2/3, x≥-3, x<0
+)TH4: -(x+3)-x-3x=1, x+3<0, x<0
x=-4/5, x<-3, x<0
⇒ x=2, x ∈ [0, +∞]
x=2
⇒ x=-4/3, x ∈ ∅
x ∈ ∅
⇒ x=2/3, x ∈ [-3, 0]
x ∈ ∅
⇒ x=-4/5, x ∈ [-∞, -3]
x ∈ ∅
⇔ x=2
x ∈ ∅
x ∈ ∅
x ∈ ∅
Vậy x=2
b,c,d làm tương tự như câu a