`x+6=y(x-1)`
`⇒x+6-y(x-1)=0`
`⇒x-1-y(x-1)=-7`
`⇒(x-1)(1-y)=-7`
`⇒(x-1)(y-1)=7`
`⇒x-1∈Ư(7)={±1,±7}`
`+)x-1=-1⇒x=0`
`⇒y-1=-7⇒y=-6`
`+)x-1=1⇒x=2`
`⇒y-1=7⇒y=8`
`+)x-1=-7⇒x=-6`
`⇒y-1=-1⇒y=0`
`+)x-1=7⇒x=8`
`⇒y-1=1⇒y=2`
Vậy `(x,y)` là:`(0,-6);(2,8);(-6,0);(8,2)`