-1x2 -10x +11 = 0
ax2 bx c = 0
a = -1
b = -10
c = 11
Δ = b2-4ac
Δ = -10² - (4 * -1 * 11)
Δ = 100 - (4*-11)
Δ = 100 - (-44)
Δ = 144 Δ > 0
-x2-10x+11=0
x = -b ∓ √Δ 2a
x' = 10 - √144 2*-1 = 10 - 12.0 -2 = -2.0 -2 = 1.0
x" = 10 + √144 2*-1 = 10 + 12.0 -2 = 22.0 -2 = -11.0
x' = 1.0
x" = -11.0
S = {x ∈ R / x' = 1.0, x" = -11.0 }