a: xy=-3
=>\(\left(x,y\right)\in\left\{\left(1;-3\right);\left(-3;1\right);\left(-1;3\right);\left(3;-1\right)\right\}\)
b: (x-1)(y+1)=19
=>\(\left(x-1;y+1\right)\in\left\{\left(1;19\right);\left(19;1\right);\left(-1;-19\right);\left(-19;-1\right)\right\}\)
=>\(\left(x,y\right)\in\left\{\left(2;18\right);\left(20;0\right);\left(0;-20\right);\left(-18;-2\right)\right\}\)
c: x(y-3)=-8
=>\(\left(x;y-3\right)\in\left\{\left(1;-8\right);\left(-8;1\right);\left(-1;8\right);\left(8;-1\right);\left(2;-4\right);\left(-4;2\right);\left(-2;4\right);\left(4;-2\right)\right\}\)
=>\(\left(x,y\right)\in\left\{\left(1;-5\right);\left(-8;4\right);\left(-1;11\right);\left(8;2\right);\left(2;-1\right);\left(-4;5\right);\left(-2;7\right);\left(4;1\right)\right\}\)
