a) x2 - x(x-3) = 6
⇔ x2-x2+3x=6
⇔ 3x=6
⇔x=2
vậy x=2
b) ( x- 3 )( x +2 ) - x -2 = 0
⇔ (x-3)(x+2)-(x+2)=0
⇔(x+2)(x-3-1)=0
⇔(x+2)(x-4)=0
⇔\(\left[{}\begin{matrix}x+2=0\\x-4=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)
vậy \(\left[{}\begin{matrix}x=-2\\x=4\end{matrix}\right.\)
