x(x - 4) - 2x + 8 = 0
<=> x(x - 4) - 2(x - 4) = 0
<=> (x - 2)(x - 4) = 0
<=> \(\left[{}\begin{matrix}x-2=0\\x-4=0\end{matrix}\right.\)
<=> \(\left[{}\begin{matrix}x=2\\x=4\end{matrix}\right.\)
\(x\left(x-4\right)-2x+8=0\)
\(\Leftrightarrow x\left(x-4\right)-2\left(x-4\right)=0\)
\(\Leftrightarrow\left(x-4\right)\left(x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=2\end{matrix}\right.\)