The teacher will be very surprised to see your correct solution 😉
a*x^2 + b*x + c = 0
D = b^2 - 4 * a * c =
(-16)^2 - 4 * (1) * (4) = 240
x1 = (-b + sqrt(D)) / (2*a)
x2 = (-b - sqrt(D)) / (2*a)
sum
____ ____ 8 - 2*\/ 15 + 8 + 2*\/ 15
=
16
product
/ ____\ / ____\ \8 - 2*\/ 15 /*\8 + 2*\/ 15 /
=
4
4
____ x1 = 8 - 2*\/ 15
____ x2 = 8 + 2*\/ 15
x2 = 2*sqrt(15) + 8