Lời giải:
`i) xy-6y+2x-12`
`=y(x-6)+2(x-6)`
`=(x-6)(y+2)`
`ii) 2x(y-z)+(z-y)(x+y)`
`=-2x(z-y)+(z-y)(x+y)`
`=(z-y)(-2x+x+y)`
`=(z-y)(y-x)`
`b)`
`x+3=(x+3)^2`
`-> (x+3)-(x+3)^2=0`
`-> (x+3)(1-x-3)=0`
`-> (x+3)(-2-x)=0`
`->` \(\left[ \begin{array}{l}x+3=0\\-2-x=0\end{array} \right.\)
`->` \(\left[ \begin{array}{l}x=-3\\-2\end{array} \right.\)