-9x2 -8x +1 = 0
ax2 bx c = 0
a = -9
b = -8
c = 1
Δ = b2-4ac
Δ = -8² - (4 * -9 * 1)
Δ = 64 - (4*-9)
Δ = 64 - (-36)
Δ = 100 Δ > 0
-9x2-8x+1=0
x = -b ∓ √Δ 2a
x' = 8 - √100 2*-9 = 8 - 10.0 -18 = -2.0 -18 = 0.111111111111
x" = 8 + √100 2*-9 = 8 + 10.0 -18 = 18.0 -18 = -1.0
x' = 9.0
x" = -81.0
S = {x ∈ R / x' = 9.0, x" = -81.0 }