Question

x( x – 4) - 2x + 8 = 0

Answer 1

 x(x-4)=2x-8
=> x^2-4x-2x+8=0
=> x^2-6x+8=0
=> x^2-6x+9 - 1 =0
=> (x-3)^2-1^2=0
=> (x-3-1)(x-3+1)=0
=>(x-4)(x-2)=0
=> x= 4 hoặc x= 2.

Answer 2

\(x\left(x-4\right)-2x+8=0\)

\(\Leftrightarrow x\left(x-4\right)-2\left(x-4\right)=0\)

\(\Leftrightarrow\left(x-4\right)\left(x-2\right)=0\)

\(\Leftrightarrow\left[{}\begin{matrix}x=4\\x=2\end{matrix}\right.\)