a) \(\left|x+4\right|\)<3
x+4<3 , x+4≥0
-(x+4) < 3, x+4<0
x<-1,x≥-4
x>-7, x<-4
x∈\(\left\{-4,-1\right\}\)
x∈\(\left\{-7,-4\right\}\)
⇒ x ∈ \(\left\{-7,-1\right\}\)
b) \(\left|x+3\right|=x-1\)
\(\left|x+3\right|-x=-1\)
x+3-x=-1,x+3≥0
-(x+3)-x=-1,x+3<0
x∈∅,x≥-3
x=-1,x<-3
⇒x∈∅
