Sửa đề: \(x^4-4x^3+8x-5=0\)
\(\Leftrightarrow x^4-x^3-3x^3+3x+5x-5=0\)
\(\Leftrightarrow\left(x-1\right)\left(x^3-3x^2-3x+5\right)=0\)
\(\Leftrightarrow\left(x-1\right)^2\cdot\left(x^2-2x-5\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=1\\x=\sqrt{6}+1\\x=-\sqrt{6}+1\end{matrix}\right.\)