{3x + y = -1
{x - xy = 8
y = -1 - 3x
x - x( -1 - 3x) = 8
x + x + 3x² = 8
3x² + 2x - 8 = 0
D = (2)² - 4*3*(-8) = 4 + 96 = 100
D = 10
x1,2 = -2+-10/2*3
x1 = -2-10/6 = -12/6 = -2
x2 = -2+10/6 = 8/6 = 4/3
y1 = -1-3*(-2)=-1+6 = 5
y2 = -1-3*4/3 = -5
Ответ:(-2;5),(4/3;-5)