-4x2 +14x +18 = 0
ax2 bx c = 0
a = -4
b = 14
c = 18
Δ = b2-4ac
Δ = 14² - (4 * -4 * 18)
Δ = 196 - (4*-72)
Δ = 196 - (-288)
Δ = 484 Δ > 0
-4x2+14x+18=0
x = -b ∓ √Δ 2a
x' = -14 - √484 2*-4 = -14 - 22.0 -8 = -36.0 -8 = 4.5
x" = -14 + √484 2*-4 = -14 + 22.0 -8 = 8.0 -8 = -1.0
x' = 72.0
x" = -16.0
S = {x ∈ R / x' = 72.0, x" = -16.0 }