-9x2 -9x +18 = 0
ax2 bx c = 0
a = -9
b = -9
c = 18
Δ = b2-4ac
Δ = -9² - (4 * -9 * 18)
Δ = 81 - (4*-162)
Δ = 81 - (-648)
Δ = 729 Δ > 0
-9x2-9x+18=0
x = -b ∓ √Δ 2a
x' = 9 - √729 2*-9 = 9 - 27.0 -18 = -18.0 -18 = 1.0
x" = 9 + √729 2*-9 = 9 + 27.0 -18 = 36.0 -18 = -2.0
x' = 81.0
x" = -162.0
S = {x ∈ R / x' = 81.0, x" = -162.0 }