-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 = -36.0 -36 = 1.0
x" = -14 + √484 2*-18 = -14 + 22.0 -36 = 8.0 -36 = -0.222222222222
x' = 324.0
x" = -72.0
S = {x ∈ R / x' = 324.0, x" = -72.0 }