Answer:
x² + 2y = 0
x² - 6x - y = 0
y = x² - 6x
x² + 2(x² - 6x) = 0
x² + 2x² - 12x = 0
3x² - 12x = 0
3x(x - 4) = 0
x = 0, 4
{(0, 0), (4, -8)}