Question

sistemas do 2 grau
x+y=6
xy=8

Answer 1

x=6-y

Substituindo:

y(6-y)=8
6y-y²-8=0
-y²+6y-8=0

Δ = 6² - 4.(-1).(-8)=36-32=4

y = (-6+-√4)/2
y = (-6 +-2)/2

y' = -8/2 = -4
y" =  -4/2 = -2

S={-4,-2}