-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 = -22.0 -2 = 11.0
x" = -10 + √144 2*-1 = -10 + 12.0 -2 = 2.0 -2 = -1.0
x' = 11.0
x" = -1.0
S = {x ∈ R / x' = 11.0, x" = -1.0 }