Tìm số nguyên x, y, biết: xy - 2y + x - 3 = 0
( x - 2 ) y + x - 3 = 0
( x - 2 ) y + x - 0 - 3 = 0
x - 2 = 0
x = 0 + 2
x = 2
y + 1 = 0
y = 0 - 1
y = -1.
xy-2y+x-3=0
\(=>x\left(y-1\right)+2y-2=1\)
\(x\left(y-1\right)+2\left(y-1\right)=1\)
\(=>\left(x+2\right)\left(y-1\right)=1\)
\(=>\left[{}\begin{matrix}x+2=1\\x+2=-1\\y-1=1\\y-1=-1\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-1\\x=-3\\y=2\\y=0\end{matrix}\right.\)