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) * (5) = -11
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
____ 3 I*\/ 11 x1 = - - -------- 2 2
____ 3 I*\/ 11 x2 = - + -------- 2 2
x2 = 3/2 + sqrt(11)*i/2
sum
____ ____ 3 I*\/ 11 3 I*\/ 11 - - -------- + - + -------- 2 2 2 2
=
3
product
/ ____\ / ____\ |3 I*\/ 11 | |3 I*\/ 11 | |- - --------|*|- + --------| \2 2 / \2 2 /
=
5
5
x1 = 1.5 - 1.6583123951777*i
x2 = 1.5 + 1.6583123951777*i
x2 = 1.5 + 1.6583123951777*i