x3 - 5x2 + 8x - 4 = 0
<=> x3 -2x2 - 3x2 + 6x + 2x - 4 = 0
<=> x2( x - 2 ) - 3x( x - 2 ) + 2( x - 2 ) = 0
<=> ( x - 2 )( x2 - 3x + 2 ) = 0
<=> ( x - 2 )2( x - 1 ) = 0
<=> \(\left[{}\begin{matrix}x-2=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=1\end{matrix}\right.\)