-1x2 -6x -8 = 0
ax2 bx c = 0
a = -1
b = -6
c = -8
Δ = b2-4ac
Δ = -6² - (4 * -1 * -8)
Δ = 36 - (4*8)
Δ = 36 - (32)
Δ = 4 Δ > 0
-x2-6x-8=0
x = -b ∓ √Δ 2a
x' = 6 - √4 2*-1 = 6 - 2.0 -2 = 4.0 -2 = -2.0
x" = 6 + √4 2*-1 = 6 + 2.0 -2 = 8.0 -2 = -4.0
x' = -2.0
x" = -4.0
S = {x ∈ R / x' = -2.0, x" = -4.0 }