-3x2 -12x -9 = 0
ax2 bx c = 0
a = -3
b = -12
c = -9
Δ = b2-4ac
Δ = -12² - (4 * -3 * -9)
Δ = 144 - (4*27)
Δ = 144 - (108)
Δ = 36 Δ > 0
-3x2-12x-9=0
x = -b ∓ √Δ 2a
x' = 12 - √36 2*-3 = 12 - 6.0 -6 = 6.0 -6 = -1.0
x" = 12 + √36 2*-3 = 12 + 6.0 -6 = 18.0 -6 = -3.0
x' = -9.0
x" = -27.0
S = {x ∈ R / x' = -9.0, x" = -27.0 }