xy - x +5y - 7 = 0
⇔(xy−x)+(5y−5)=2⇔(xy−x)+(5y−5)=2
⇔x(y−1)+5(y−1)=2⇔x(y−1)+5(y−1)=2
⇔(y−1)(x+5)=2⇔(y−1)(x+5)=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.
Vậy ...
à mk nhầm tí x*y-x+5*y-7 nhk các bn
x(y-1)+5(y-1)=2
(y-1)(x+5)=2.1=-1.-2
Th1:y-1=1 <=> y=2
x+5=2 <=> x=-3
Th2 y-1=2 <=> y=3
x+5=1<=> x=-4
Th3 y-1=-1 <=> y=0
x+5=-2 <=> x=-7
Th4 y-1=-2 <=> y=-1
x+5=-1<=> x=-6