Ta có: \(xy+3x-y=6\)
\(\Rightarrow x\left(y+3\right)-y=6\)
\(\Rightarrow x\left(y+3\right)-y-3=6-3=3\)
\(\Rightarrow x\left(y+3\right)-\left(y+3\right)=3\)
\(\Rightarrow\left(x-1\right)\left(y+3\right)=3\)
\(\Rightarrow\left(x-1\right)và\left(y+3\right)\inƯ\left(3\right)\)
Ta có bảng sau: Vậy ta tìm được 4 cặp (x,y): \(\left\{2;0\right\};\left\{0;-6\right\};\left\{4;-2\right\};\left\{-2;-4\right\}\)