Given that a, B and C are the three roots of the equation x ^ 3 + PX + q = 0, how to get a + B + C = 0 according to the relationship between the root and the coefficient Such as the title

Given that a, B and C are the three roots of the equation x ^ 3 + PX + q = 0, how to get a + B + C = 0 according to the relationship between the root and the coefficient Such as the title

Weida's theorem
A + B + C = - quadratic coefficient / cubic coefficient = - 0 / 1 = 0