x2 x =0

-4x2 -4x -1 = 0

ax2 bx c = 0

a = -4

b = -4

c = -1

Δ = b2-4ac

Δ = -4² - (4 * -4 * -1)

Δ = 16 - (4*4)

Δ = 16 - (16)

Δ = 0      Δ = 0

x = -b 2*a

x = 4 2*-4

x = -0.5

S = {x ∈ R / x = -0.5}