-4x2-16x-16=0

Δ = b2-4ac

Δ = -16² - (4 * -4 * -16)

Δ = 256 - (4*64)

Δ = 256 - (256)

Δ = 0      Δ = 0

x = -b 2*a

x = 16 2*-4

x = -2.0

S = {x ∈ R / x = -2.0}