-4x2 +6x +18 = 0
ax2 bx c = 0
a = -4
b = 6
c = 18
Δ = b2-4ac
Δ = 6² - (4 * -4 * 18)
Δ = 36 - (4*-72)
Δ = 36 - (-288)
Δ = 324 Δ > 0
-4x2+6x+18=0
x = -b ∓ √Δ 2a
x' = -6 - √324 2*-4 = -6 - 18.0 -8 = -24.0 -8 = 3.0
x" = -6 + √324 2*-4 = -6 + 18.0 -8 = 12.0 -8 = -1.5
x' = 48.0
x" = -24.0
S = {x ∈ R / x' = 48.0, x" = -24.0 }