5x2 -16x -16 = 0
ax2 bx c = 0
a = 5
b = -16
c = -16
Δ = b2-4ac
Δ = -16² - (4 * 5 * -16)
Δ = 256 - (4*-80)
Δ = 256 - (-320)
Δ = 576 Δ > 0
5x2-16x-16=0
x = -b ∓ √Δ 2a
x' = 16 - √576 2*5 = 16 - 24.0 10 = -8.0 10 = -0.8
x" = 16 + √576 2*5 = 16 + 24.0 10 = 40.0 10 = 4.0
x' = -20.0
x" = 100.0
S = {x ∈ R / x' = -20.0, x" = 100.0 }