-12x2-12x-3=0

Δ = b2-4ac

Δ = -12² - (4 * -12 * -3)

Δ = 144 - (4*36)

Δ = 144 - (144)

Δ = 0      Δ = 0

x = -b 2*a

x = 12 2*-12

x = -0.5

S = {x ∈ R / x = -0.5}