xy - x +5y - 7 = 0
\(\Leftrightarrow\left(xy-x\right)+\left(5y-5\right)=2\)
\(\Leftrightarrow x\left(y-1\right)+5\left(y-1\right)=2\)
\(\Leftrightarrow\left(y-1\right)\left(x+5\right)=2\)
Có 4 TH xảy ra:
TH1: x + 5 = 2, y - 1 = 1 x = -3, y = 2
TH2: x + 5 = 1, y - 1 = 2 x = - 4, y = 3
TH3: x + 5 = -2, y - 1 = -1 x = -7, y = 0
TH4: x + 5 = -1, y - 1 = -2 x = -6, y = -1.
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