Ta có:
b,
`(2x-8)(x-11)=0`
⇔\(\left[ \begin{array}{l}2x-8=0\\x-11=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=4\\x=11\end{array} \right.\)
c,
`x.x-2.x=0`
⇔`x(x-2)=0`
⇔\(\left[ \begin{array}{l}x=0\\x-2=0\end{array} \right.\)
⇔\(\left[ \begin{array}{l}x=0\\x=2\end{array} \right.\)
d,
`xy-x-y+1=0`
⇔`x(y-1)-(y-1)=0`
⇔`(x-1)(y-1)=0`
⇔\(\left[ \begin{array}{l}x-1=0\\y-1=0\end{array} \right.\)
\(\left[ \begin{array}{l}x=1\\y=1\end{array} \right.\)
