refer
(x−1)(y+1)=5(x−1)(y+1)=5
⇒x−1,y+1∈Ư(5)={±1;±5}⇒x−1,y+1∈Ư(5)={±1;±5}
Có :
| x-1 | -5 | -1 | 1 | 5 |
| x | -4 | 0 | 2 | 6 |
| y+1 | -1 | -5 | 5 | 1 |
| y | -2 | -6 | 4 | 0 |
`(x-1)(y+1)=5`
`=>x-1;y+1 in Ư(5)={+-1;+-5}`
`x-1=1`
`x=2`
`x-1=-1`
`x=0`
`x-1=5`
`x=6`
`x-1=-5`
`x=-4`
_____________
`y+1=1`
`y=0`
`y+1=-1`
`y=-2`
`y+1=5`
`y=4`
`y+1=-5`
`y=-6`
Có:
+ \(5⋮\left(x-1\right)\)
\(\Rightarrow\left(x-1\right)\inƯ_{\left(5\right)}\)
\(\Rightarrow\left[{}\begin{matrix}x-1=1\\x-1=5\\x-1=-1\\x-1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=2\\x=6\\x=0\\x=-4\end{matrix}\right.\)
+ \(5⋮\left(y+1\right)\)
\(\Rightarrow\left(y+1\right)\inƯ_{\left(5\right)}\)
\(\Rightarrow\left[{}\begin{matrix}y+1=1\\y+1=5\\y+1=-1\\y+1=-5\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}y=0\\y=4\\y=-2\\y=-6\end{matrix}\right.\)
