x^2-xy=12-y^2
x-2y=6
x^2-xy=12-y^2
x=6+2y
(6+2y)^2-(6+2y)y=12-y^2
36+24y + 4y^2 - 6y - 2y^2 - 12 +y^2 = 0
3y^2 + 18y +24 = 0
y^2 + 6y +8=0
y1 = -4
y2 = -2
x1=6+2*(-4)= -2
x2 = 6+2*(-2) = 2
x^2 - xy = 12 - y^2
x - 2y = 6
x^2 - xy = 12 - y^2
x = 6 + 2y
Подставляем х.
(6 + 2y)^2 - y(6+2y) = 12 - y^2
x = 6 + 2y
36 + 24y + 4y^2 - 6y - 2y^2 - 12 + y^2 = 0
x = 6 + 2y
3y^2 + 18y + 24 = 0
Выносим 3 за скобку:
3(y^2 + 6y + 8) = 0
y^2 + 6y + 8 = 0
D = 36 - 4*8 = 4 = 2^2
y1 = (-6 + 2) / 2 = -2
y2 = (-6 - 2) / 2 = -4
Подставляем значения...
y = -2
x = 6 - 4 = 2
y = -4
x = 6 - 8 = -2
ответ: (2 ; -2) и (-2 ; -4)
