Решите систему уравнений:

xy+x-y=1

x²y-xy²=-6

Xy + (x-y) = 1

xy (x-y) = - 6

xy=a x-y=b

a+b=1⇒a=1-b

a*b=-6

b (1-b) = - 6

b²-b-6=0

b1*b2=1 U b1*b2=-6

b1=-2⇒a1=3

x-y=-2 U xy=3

x=y-2

y²-2y-3=0

y1+y2=2 U y1*y2=-3

y1=3⇒x1=1

y2=-1⇒x2=-3

b2=3⇒a2=-2

x-y=3 U xy=-2

x=y+3

y²+3y+2=0

y3+y4=-3 U y3+y4=2

y3=-2⇒x3=1

y4=-1⇒x4=2

(1; 3) (-3; -1) (1; -2) (2; -1)