\(x^2-1=2x\sqrt{x^2+2x}\)
\(\Rightarrow\left(x-1\right)\left(x+1\right)-2x\sqrt{x}.\sqrt{x+1}=0\)
\(\Rightarrow\sqrt{x-1}\left(\sqrt{x+1}\left(x+1\right)-2x\sqrt{x}\right)=0\)
\(\Rightarrow\sqrt{x-1}\left(x+1\right)-2x\sqrt{x}=0\)
Bình phương 2 vế là ra nha