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 }