-18x2 -14x +4 = 0
ax2 bx c = 0
a = -18
b = -14
c = 4
Δ = b2-4ac
Δ = -14² - (4 * -18 * 4)
Δ = 196 - (4*-72)
Δ = 196 - (-288)
Δ = 484 Δ > 0
-18x2-14x+4=0
x = -b ∓ √Δ 2a
x' = 14 - √484 2*-18 = 14 - 22.0 -36 = -8.0 -36 = 0.222222222222
x" = 14 + √484 2*-18 = 14 + 22.0 -36 = 36.0 -36 = -1.0
x' = 72.0
x" = -324.0
S = {x ∈ R / x' = 72.0, x" = -324.0 }