-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 = -8.0 -8 = 1.0
x" = 14 + √484 2*-4 = 14 + 22.0 -8 = 36.0 -8 = -4.5
x' = 16.0
x" = -72.0
S = {x ∈ R / x' = 16.0, x" = -72.0 }