-4x2 -20x -16 = 0
ax2 bx c = 0
a = -4
b = -20
c = -16
Δ = b2-4ac
Δ = -20² - (4 * -4 * -16)
Δ = 400 - (4*64)
Δ = 400 - (256)
Δ = 144 Δ > 0
-4x2-20x-16=0
x = -b ∓ √Δ 2a
x' = 20 - √144 2*-4 = 20 - 12.0 -8 = 8.0 -8 = -1.0
x" = 20 + √144 2*-4 = 20 + 12.0 -8 = 32.0 -8 = -4.0
x' = -16.0
x" = -64.0
S = {x ∈ R / x' = -16.0, x" = -64.0 }