Bài 1 : Tìm x,y thuộc Z :
1,( x + 1 ) . ( y - 2 ) = 0
2,( x - 5 ) . ( y - 7 ) = 1
3,( x + 4 ) . ( y - 2 ) = 2
4,( x - 4 ) . ( y + 3 ) = -3
5,( x + 3 ) . ( y - 6 ) = -4
6,( x - 8 ) . ( y + 7 ) = 5
7,( x + 7 ) . ( y - 3 ) = -6
8,( x - 6 ) . ( y + 2 ) = 7
1)\(\left(x+1\right).\left(y-2\right)=0\) \(\left(x,y\inℤ\right)\)
\(\Rightarrow\orbr{\begin{cases}x+1=0\\y-2=0\end{cases}}\Rightarrow\orbr{\begin{cases}x=-1\\y=2\end{cases}}\)
2)\(\left(x-5\right).\left(y-7\right)=1\)
3)\(\left(x+4\right).\left(y-2\right)=2\)
4)\(\left(x-4\right).\left(y+3\right)=-3\)
5)\(\left(x+3\right).\left(y-6\right)=-4\)
6)\(\left(x-8\right).\left(y+7\right)=5\)
7)\(\left(x+7\right).\left(y-3\right)=-6\)
8)\(\left(x-6\right).\left(y+2\right)=7\)
ok :)