-1x2 -5x -4 = 0
ax2 bx c = 0
a = -1
b = -5
c = -4
Δ = b2-4ac
Δ = -5² - (4 * -1 * -4)
Δ = 25 - (4*4)
Δ = 25 - (16)
Δ = 9 Δ > 0
-x2-5x-4=0
x = -b ∓ √Δ 2a
x' = 5 - √9 2*-1 = 5 - 3.0 -2 = 2.0 -2 = -1.0
x" = 5 + √9 2*-1 = 5 + 3.0 -2 = 8.0 -2 = -4.0
x' = -1.0
x" = -4.0
S = {x ∈ R / x' = -1.0, x" = -4.0 }