-9x2 +11x -2 = 0
ax2 bx c = 0
a = -9
b = 11
c = -2
Δ = b2-4ac
Δ = 11² - (4 * -9 * -2)
Δ = 121 - (4*18)
Δ = 121 - (72)
Δ = 49 Δ > 0
-9x2+11x-2=0
x = -b ∓ √Δ 2a
x' = -11 - √49 2*-9 = -11 - 7.0 -18 = -18.0 -18 = 1.0
x" = -11 + √49 2*-9 = -11 + 7.0 -18 = -4.0 -18 = 0.222222222222
x' = 81.0
x" = 18.0
S = {x ∈ R / x' = 81.0, x" = 18.0 }