-12x2 +6x +18 = 0
ax2 bx c = 0
a = -12
b = 6
c = 18
Δ = b2-4ac
Δ = 6² - (4 * -12 * 18)
Δ = 36 - (4*-216)
Δ = 36 - (-864)
Δ = 900 Δ > 0
-12x2+6x+18=0
x = -b ∓ √Δ 2a
x' = -6 - √900 2*-12 = -6 - 30.0 -24 = -36.0 -24 = 1.5
x" = -6 + √900 2*-12 = -6 + 30.0 -24 = 24.0 -24 = -1.0
x' = 216.0
x" = -144.0
S = {x ∈ R / x' = 216.0, x" = -144.0 }