The teacher will be very surprised to see your correct solution 😉
a*x^2 + b*x + c = 0
D = b^2 - 4 * a * c =
(3)^2 - 4 * (1) * (18) = -63
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
___ 3 3*I*\/ 7 x1 = - - - --------- 2 2
___ 3 3*I*\/ 7 x2 = - - + --------- 2 2
x2 = -3/2 + 3*sqrt(7)*i/2
sum
___ ___ 3 3*I*\/ 7 3 3*I*\/ 7 - - - --------- + - - + --------- 2 2 2 2
=
-3
product
/ ___\ / ___\ | 3 3*I*\/ 7 | | 3 3*I*\/ 7 | |- - - ---------|*|- - + ---------| \ 2 2 / \ 2 2 /
=
18
18
x1 = -1.5 + 3.96862696659689*i
x2 = -1.5 - 3.96862696659689*i
x2 = -1.5 - 3.96862696659689*i