5x2 -18x -8 = 0
ax2 bx c = 0
a = 5
b = -18
c = -8
Δ = b2-4ac
Δ = -18² - (4 * 5 * -8)
Δ = 324 - (4*-40)
Δ = 324 - (-160)
Δ = 484 Δ > 0
5x2-18x-8=0
x = -b ∓ √Δ 2a
x' = 18 - √484 2*5 = 18 - 22.0 10 = -4.0 10 = -0.4
x" = 18 + √484 2*5 = 18 + 22.0 10 = 40.0 10 = 4.0
x' = -10.0
x" = 100.0
S = {x ∈ R / x' = -10.0, x" = 100.0 }