a: \(\Leftrightarrow\left(9x-2;2y+1\right)\in\left\{\left(1;17\right);\left(17;1\right);\left(-1;-17\right);\left(-17;-1\right)\right\}\)
\(\Leftrightarrow\left(x,y\right)\in\left\{\left(\dfrac{1}{3};8\right);\left(\dfrac{19}{9};0\right);\left(\dfrac{1}{9};-9\right);\left(-\dfrac{5}{3};-1\right)\right\}\)
b: \(\Leftrightarrow xy+x+2y+2=7\)
\(\Leftrightarrow\left(y+1\right)\left(x+2\right)=7\)
\(\Leftrightarrow\left(x+2;y+1\right)\in\left\{\left(1;7\right);\left(7;1\right);\left(-1;-7\right);\left(-7;-1\right)\right\}\)
hay \(\left(x,y\right)\in\left\{\left(-1;6\right);\left(5;0\right);\left(-3;-8\right);\left(-9;-2\right)\right\}\)
