Mn giúp e với ạ . E cảm ơn mn nhiều

Bài `11`

`xy+2x-y=7`

`=>x(y+2)-(y+2)=5`

`=>(y+2)(x-1)=5`

Ta có bảng sau:

$\begin{array}{|c|c|c|}\hline \text{}y+2&\text{}1&\text{}-1&5&-5\\\hline \text{}x-1&\text{}5&\text{}-5&1&-1\\\hline \text{}y&\text{}-1&\text{}-3&3&-7\\\hline \text{}x&\text{}6&\text{}-4&2&0\\\hline\end{array}$

Vậy `(x,y)in{(6,-1);(-4,-3);(2,3);(0,-7)}`$\\$

Bài `12`

`2xy-x-y=2`

`=> 4xy - 2x - 2y = 4`

`=> 2x(2y-1) - (2y-1) = 5`

`=> (2y-1)(2x-1) = 5`

Ta có bảng sau:

$\begin{array}{|c|c|c|}\hline \text{}2y-1&\text{1}&\text{}-1&\text{5}&\text{}-5\\\hline \text{}2x-1&\text{5}&\text{}-5&\text{1}&\text{}-1\\\hline \text{}y&\text{1}&\text{0}&\text{3}&\text{}-2\\\hline\text{}x&\text{3}&\text{}-2&\text{1}&\text{0}\\\hline\end{array}$

`(y,x) = {(1,3) ; (0,-2) ; (3,1) ; (-2,0)}`$\\$

Bài `14`

`2xy+x-2y=4`

`=>x(2y+1)-(2y+1)=3`

`=>(2y+1)(x-1)=3`

Ta có bảng sau:

$\begin{array}{|c|c|c|}\hline \text{}x-1&\text{}1&\text{}-1&3&-3\\\hline \text{}2y+1&\text{}3&\text{}-3&1&-1\\\hline \text{}x&\text{}2&\text{}0&4&-2\\\hline \text{}2y&\text{}2&\text{}-4&0&-2\\\hline \text{}y&\text{}1&\text{}-2&0&-1\\\hline\end{array}$

Vậy `(x,y)in{(2,1);(0,-2);(4,0);(-2,-1)}`$\\$

Bài `15`

`x+y+xy=2`

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

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

Ta có bảng sau:

$\begin{array}{|c|c|c|}\hline \text{}y+1&\text{}1&\text{}-1&3&-3\\\hline \text{}x+1&\text{}3&\text{}-3&1&-1\\\hline \text{}x&\text{}2&\text{}-4&0&-2\\\hline \text{}y&\text{}0&\text{}-2&2&-4\\\hline\end{array}$

Vậy `(x,y)in{(2,0);(-4,-2);(0,2);(-2,-4)}`