Hi,
quadratic equations may have zero, one or two real solutions
Examples:
y = x^2 + 4 NO real solutions (Green) 0 = x^2+4, x^2 = -4, x = ± 2i
y = x^2 1 real solutions x = 0 (Blue) 0 = x^2, x = 0
y = x^2 - 4 2 real solutions x = ± 2 (Purple), 0 = x^2-4, x^2 = 4
