ab=2a-b
=>ab-2a+b=0
=>a(b-2)+b-2=-2
=>(b-2)(a+1)=-2
=>\(\left(a+1;b-2\right)\in\left\{\left(1;-2\right);\left(-2;1\right);\left(2;-1\right);\left(-1;2\right)\right\}\)
=>\(\left(a;b\right)\in\left\{\left(0;0\right);\left(-3;3\right);\left(1;1\right);\left(-2;4\right)\right\}\)
ab=2a-b
=>ab-2a+b=0
=>a(b-2)+b-2=-2
=>(b-2)(a+1)=-2
=>(a+1;b−2)∈{(1;−2);(−2;1);(2;−1);(−1;2)}(�+1;�−2)∈{(1;−2);(−2;1);(2;−1);(−1;2)}
=>(a;b)∈{(0;0);(−3;3);(1;1);(−2;4)}