\(\Leftrightarrow2\left(x-2\right)^2-4\left(x-2\right)\sqrt{x+1}-\left(x-2\right)\sqrt{x+1}+2\sqrt{\left(x+1\right)^2}=0\)
=>\(2\left(x-2\right)\left(x-2-2\sqrt{x+1}\right)-\sqrt{x+1}\left(x-2-2\sqrt{x+1}\right)=0\)
=>\(\left(x-2-2\sqrt{x+1}\right)\left(2x-4-\sqrt{x+1}\right)=0\)
=>x(x-8)=0 hoặc 4x^2-17x+15=0
=>x=0(loại);x=8(nhận);x=3(nhận); x=5/4(loại)
S={3;8}