5x2 -6x -11 = 0
ax2 bx c = 0
a = 5
b = -6
c = -11
Δ = b2-4ac
Δ = -6² - (4 * 5 * -11)
Δ = 36 - (4*-55)
Δ = 36 - (-220)
Δ = 256 Δ > 0
5x2-6x-11=0
x = -b ∓ √Δ 2a
x' = 6 - √256 2*5 = 6 - 16.0 10 = -10.0 10 = -1.0
x" = 6 + √256 2*5 = 6 + 16.0 10 = 22.0 10 = 2.2
x' = -25.0
x" = 55.0
S = {x ∈ R / x' = -25.0, x" = 55.0 }