\(\sqrt{x^2-4x+4}-\sqrt{x^2+4x+4}=\sqrt{\left(x-2\right)^2}-\sqrt{\left(x+2\right)^2}=\left|x-2\right|-\left|x+2\right|\)
1. Với \(x\ge2\)thì :
\(B=\left(x-2\right)-\left(x+2\right)=x-2-x-2=-4\)
2. Với \(x\le-2\)thì :
\(B=\left(2-x\right)-\left(-x-2\right)=2-x+x+2=4\)
3. Với \(-2< x< 2\)thì
\(\left(2-x\right)-\left(x+2\right)=2-x-x-2=-2x\)