-9x2 -11x -2 = 0
ax2 bx c = 0
a = -9
b = -11
c = -2
Δ = b2-4ac
Δ = -11² - (4 * -9 * -2)
Δ = 121 - (4*18)
Δ = 121 - (72)
Δ = 49 Δ > 0
-9x2-11x-2=0
x = -b ∓ √Δ 2a
x' = 11 - √49 2*-9 = 11 - 7.0 -18 = 4.0 -18 = -0.222222222222
x" = 11 + √49 2*-9 = 11 + 7.0 -18 = 18.0 -18 = -1.0
x' = -18.0
x" = -81.0
S = {x ∈ R / x' = -18.0, x" = -81.0 }