Ta có :
\(\left(x-1\right).\left(y+2\right)=5\)
Vì \(x,y\in Z\Leftrightarrow x-1;y+2\in Z;x-1;y+2\inƯ\left(5\right)\)
\(\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}x-1=1\\y+2=5\end{matrix}\right.\\\left[{}\begin{matrix}x-1=5\\y+2=1\end{matrix}\right.\\\left[{}\begin{matrix}x-1=-1\\y+2=-5\end{matrix}\right.\\\left[{}\begin{matrix}x-1=-5\\y+2=-1\end{matrix}\right.\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}\left[{}\begin{matrix}x=2\\y=3\end{matrix}\right.\\\left[{}\begin{matrix}x=6\\y=-1\end{matrix}\right.\\\left[{}\begin{matrix}x=0\\y=-7\end{matrix}\right.\\\left[{}\begin{matrix}x=-4\\y=-3\end{matrix}\right.\end{matrix}\right.\)
Vậy ....
(x-1).(y+2)=5
x-1 =5
x=5+1
x=6
Hoặc:y+2=5
y=5-2
y=3
Vậy xbằng 6 hoặc y bằng 5
Chúc bạn học tốt
