-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 = -24.0 -24 = 1.0

x" = 6 + √900 2*-12 = 6 + 30.0 -24 = 36.0 -24 = -1.5

x' = 144.0

x" = -216.0

S = {x ∈ R / x' = 144.0, x" = -216.0 }