x2 x =0

-1x2 -4x -4 = 0

ax2 bx c = 0

a = -1

b = -4

c = -4

Δ = b2-4ac

Δ = -4² - (4 * -1 * -4)

Δ = 16 - (4*4)

Δ = 16 - (16)

Δ = 0      Δ = 0

x = -b 2*a

x = 4 2*-1

x = -2.0

S = {x ∈ R / x = -2.0}