-1x2 -6x -5 = 0
ax2 bx c = 0
a = -1
b = -6
c = -5
Δ = b2-4ac
Δ = -6² - (4 * -1 * -5)
Δ = 36 - (4*5)
Δ = 36 - (20)
Δ = 16 Δ > 0
-x2-6x-5=0
x = -b ∓ √Δ 2a
x' = 6 - √16 2*-1 = 6 - 4.0 -2 = 2.0 -2 = -1.0
x" = 6 + √16 2*-1 = 6 + 4.0 -2 = 10.0 -2 = -5.0
x' = -1.0
x" = -5.0
S = {x ∈ R / x' = -1.0, x" = -5.0 }