The teacher will be very surprised to see your correct solution 😉
a*x^2 + b*x + c = 0
D = b^2 - 4 * a * c =
(-1)^2 - 4 * (1) * (-4) = 17
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
____ 1 \/ 17 x1 = - - ------ 2 2
____ 1 \/ 17 x2 = - + ------ 2 2
x2 = 1/2 + sqrt(17)/2
sum
____ ____ 1 \/ 17 1 \/ 17 - - ------ + - + ------ 2 2 2 2
=
1
product
/ ____\ / ____\ |1 \/ 17 | |1 \/ 17 | |- - ------|*|- + ------| \2 2 / \2 2 /
=
-4
-4