18x2 -16x -2 = 0
ax2 bx c = 0
a = 18
b = -16
c = -2
Δ = b2-4ac
Δ = -16² - (4 * 18 * -2)
Δ = 256 - (4*-36)
Δ = 256 - (-144)
Δ = 400 Δ > 0
18x2-16x-2=0
x = -b ∓ √Δ 2a
x' = 16 - √400 2*18 = 16 - 20.0 36 = -4.0 36 = -0.111111111111
x" = 16 + √400 2*18 = 16 + 20.0 36 = 36.0 36 = 1.0
x' = -36.0
x" = 324.0
S = {x ∈ R / x' = -36.0, x" = 324.0 }