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 = -22.0 10 = -2.2
x" = -6 + √256 2*5 = -6 + 16.0 10 = 10.0 10 = 1.0
x' = -55.0
x" = 25.0
S = {x ∈ R / x' = -55.0, x" = 25.0 }