-9x2 +x +10 = 0
ax2 bx c = 0
a = -9
b = 1
c = 10
Δ = b2-4ac
Δ = ² - (4 * -9 * 10)
Δ = 1 - (4*-90)
Δ = 1 - (-360)
Δ = 361 Δ > 0
-9x2+x+10=0
x = -b ∓ √Δ 2a
x' = -1 - √361 2*-9 = -1 - 19.0 -18 = -20.0 -18 = 1.11111111111
x" = -1 + √361 2*-9 = -1 + 19.0 -18 = 18.0 -18 = -1.0
x' = 90.0
x" = -81.0
S = {x ∈ R / x' = 90.0, x" = -81.0 }