-9x2 -5x +14 = 0
ax2 bx c = 0
a = -9
b = -5
c = 14
Δ = b2-4ac
Δ = -5² - (4 * -9 * 14)
Δ = 25 - (4*-126)
Δ = 25 - (-504)
Δ = 529 Δ > 0
-9x2-5x+14=0
x = -b ∓ √Δ 2a
x' = 5 - √529 2*-9 = 5 - 23.0 -18 = -18.0 -18 = 1.0
x" = 5 + √529 2*-9 = 5 + 23.0 -18 = 28.0 -18 = -1.55555555556
x' = 81.0
x" = -126.0
S = {x ∈ R / x' = 81.0, x" = -126.0 }