t=-(0.33333 (1.7321 sqrt(-2 a_1 x + a_0 (x - 3 a_2) + a_2 x + 3 a_1^2) - 3 a_0 + 3 a_1))/(a_0 - 2 a_1 + a_2) for y = 3 * (1-t)^2 * a_0 + 6 * (1-t) * t * a_1 + 3 * t^2 * a_2