x(x-1)-4(x-1)=0
(x-4)(x-1)=0
=> x-4=0 hoặc x-1=0
=> x=4 hoặc x= 1
Vậy x = { 4;1}
\(x\left(x-1\right)-4\left(x-1\right)=0\\ \Leftrightarrow\left(x-1\right)\left(x-4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x-1=0\\x-4=0\end{matrix}\right.\Leftrightarrow}\left[{}\begin{matrix}x=1\\x=4\end{matrix}\right.\)