`x-2y+2xy=3`
`<=>x+2xy-2y=1+2`
`<=>x+2xy-2y-1=2`
`<=>(x-1)+2y(x-1)=2`
`<=>(2y+1)(x-1)=2`
`2=1*2=(-1)*(-2)`
$\left[\begin{array}{ccc}x-1&-2&-1&1&2\\2y+1&-1&-2&2&1\\x&-1&0&2&3\\y&\dfrac{-3}2&-1&0&\dfrac12\end{array}\right]$
`text{Vậy }(x;y)={(-1;-3/2);(0;-1);(2;0);(3;1/2)}`