A quadratic equation can be solved using the discriminant. The roots of the quadratic equation: z1=2aD−b z2=2a−D−b where D = b^2 - 4*a*c - it is the discriminant. Because a=1 b=6 c=13 , then
D = b^2 - 4 * a * c =
(6)^2 - 4 * (1) * (13) = -16
Because D<0, then the equation has no real roots, but complex roots is exists.
z1 = (-b + sqrt(D)) / (2*a)
z2 = (-b - sqrt(D)) / (2*a)
or z1=−3+2i z2=−3−2i
Vieta's Theorem
it is reduced quadratic equation pz+q+z2=0 where p=ab p=6 q=ac q=13 Vieta Formulas z1+z2=−p z1z2=q z1+z2=−6 z1z2=13