\(\Leftrightarrow x^4+2x^2+1=2x^2+4x+2\)
\(\Leftrightarrow\left(x^2+1\right)^2=2\left(x+1\right)^2\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+1=\sqrt{2}\left(x+1\right)\\x^2+1=-\sqrt{2}\left(x+1\right)\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-\sqrt{2}x+1-\sqrt{2}=0\\x^2+\sqrt{2}x+1+\sqrt{2}=0\end{matrix}\right.\)
Tính delta giải như pt bậc 2 bình thường