Đáp án+Giải thích các bước giải: 

Ta có : `xy+x+2y=5`

`=>(xy+x)+(2y+2)=7`

`=>x(y+1)+2(y+1)=7`

`=>(x+2)(y+1)=7`

Do `x,y in ZZ` nên ta có bảng :

\begin{array}{|c|c|c|}\hline   \text{x+2}&\text{1}&\text{7}&\text{-1}&\text{-7}\\\hline \text{y+1}&\text{7}&\text{1}&\text{-7}&\text{-1}\\\hline \text{x}&\text{-1}&\text{5}&\text{-3}&\text{-9}\\\hline \text{y}&\text{6}&\text{0}&\text{-8}&\text{-2}\\\hline\end{array}

Vậy `(x,y) in{(-1;6),(5;0),(-3;-8),(-9;-2)}`