Đáp án:

Giải thích các bước giải:

 `x + y + xy = 3` `(x,y \in Z)`

`x(1+y) + y=3`

`x(1+y) + (1+y) = 3+1`

`(x+1)(y+1) = 4`

Ta có bảng : \begin{array}{|c|c|c|}\hline \text{x+1}&\text{1}&\text{4}&\text{-1}&\text{-4}&\text{2}&\text{-2}\\\hline \text{y+1}&\text{4}&\text{1}&\text{-4}&\text{-1}&\text{2}&\text{-2}\\\hline \text{x}&\text{0}&\text{3}&\text{-2}&\text{-5}&\text{1}&\text{-3}\\\hline \text{y}&\text{3}&\text{0}&\text{-5}&\text{-2}&\text{1}&\text{-3}\\\hline \end{array}

Vậy `(x,y) \ in {(0,3);(3,0);(-2,-5);(-5,-2);(1,1);(-3,-3)}`