Đáp án:
a.(b-2)=3
TH1: $\left \{ {{a=1} \atop {b-2=3}} \right.$ =>$\left \{ {{a=1} \atop {b=5}} \right.$
TH2: $\left \{ {{a=-1} \atop {b-2=-3}} \right.$ =>$\left \{ {{a=11} \atop {b=-1}} \right.$
TH3: $\left \{ {{a=3} \atop {b-2=1}} \right.$ =>$\left \{ {{a=3} \atop {b=3}} \right.$
TH4: $\left \{ {{y=-3} \atop {b-2=-1}} \right.$ =>$\left \{ {{a=-3} \atop {b=1}} \right.$
Vậy (a,b)={(1;5);(11;-1);(3;3);(-3;1)}
