a: (x-2)(x-1)<0
=>x-1>0 và x-2<0
=>1<x<2
b: \(\Leftrightarrow x^2+2x+1+2\left|x+1\right|-3=0\)
\(\Leftrightarrow\left(\left|x+1\right|\right)^2+2\left|x+1\right|-3=0\)
\(\Leftrightarrow\left(\left|x+1\right|+3\right)\left(\left|x+1\right|-1\right)=0\)
=>x+1=1 hoặc x+1=-1
=>x=0 hoặc x=-2