Đáp án + Giải thích các bước giải:
`a)`
`xy+2y+2x=3`
`=> xy+2y+2x+4=7`
`=> y(x+2)+2(x+2)=7`
`=> (y+2)(x+2)=7`
`=> x+2;y+2 in Ư(7)`
Ta có bảng :
$\begin{array}{|c|c|}\hline x+2&-7&-1&1&7\\\hline y+2&-1&-7&7&1\\\hline x&-9&-3&-1&5 \\\hline y&-3&-9&5&-1\\\hline \end{array}$
Vậy `(x;y) in {(-9;-3);(-3;-9);(-1;5);(5;-1)}`
`b)`
`2xy+x+y=1`
`=> x(2y+1)+y=1`
`=> 2x(2y+1)+2y+1=3`
`=> (2x+1)(2y+1)=3`
`=> 2x+1; 2y+1 in Ư(3)`
$\begin{array}{|c|c|}\hline 2x+1&-3&-1&1&3\\\hline 2y+1&-1&-3&3&1\\\hline x&-2&-1&0&1 \\\hline y&-1&-2&1&0\\\hline \end{array}$
Vậy `(x;y) in {(-2;-1);(-1;-2);(0;1);(1;0)}`
