=> \(x\left(y-1\right)+2\left(y-1\right)=1\)
=> \(\left(x+2\right)\left(y-1\right)=1\)
Th1: \(\hept{\begin{cases}x+2=1\\y-1=1\end{cases}}\)=> \(\hept{\begin{cases}x=1\\y=2\end{cases}}\)
Th2: \(\hept{\begin{cases}x+2=-1\\y-1=-1\end{cases}}\)=> \(\hept{\begin{cases}x=-3\\y=0\end{cases}}\)