=>xy+x+y=12
=>y(x+1)+x+1=13
=>(x+1)(y+1)=13
=>\(\left(x+1;y+1\right)\in\left\{\left(1;13\right);\left(13;1\right);\left(-1;-13\right);\left(-13;-1\right)\right\}\)
=>\(\left(x,y\right)\in\left\{\left(0;12\right);\left(12;0\right);\left(-2;-14\right);\left(-14;-2\right)\right\}\)