-4x2 -18x -18 = 0
ax2 bx c = 0
a = -4
b = -18
c = -18
Δ = b2-4ac
Δ = -18² - (4 * -4 * -18)
Δ = 324 - (4*72)
Δ = 324 - (288)
Δ = 36 Δ > 0
-4x2-18x-18=0
x = -b ∓ √Δ 2a
x' = 18 - √36 2*-4 = 18 - 6.0 -8 = 12.0 -8 = -1.5
x" = 18 + √36 2*-4 = 18 + 6.0 -8 = 24.0 -8 = -3.0
x' = -24.0
x" = -48.0
S = {x ∈ R / x' = -24.0, x" = -48.0 }