-9x2 -2x +11 = 0
ax2 bx c = 0
a = -9
b = -2
c = 11
Δ = b2-4ac
Δ = -2² - (4 * -9 * 11)
Δ = 4 - (4*-99)
Δ = 4 - (-396)
Δ = 400 Δ > 0
-9x2-2x+11=0
x = -b ∓ √Δ 2a
x' = 2 - √400 2*-9 = 2 - 20.0 -18 = -18.0 -18 = 1.0
x" = 2 + √400 2*-9 = 2 + 20.0 -18 = 22.0 -18 = -1.22222222222
x' = 81.0
x" = -99.0
S = {x ∈ R / x' = 81.0, x" = -99.0 }