-4x2 +9x +9 = 0
ax2 bx c = 0
a = -4
b = 9
c = 9
Δ = b2-4ac
Δ = 9² - (4 * -4 * 9)
Δ = 81 - (4*-36)
Δ = 81 - (-144)
Δ = 225 Δ > 0
-4x2+9x+9=0
x = -b ∓ √Δ 2a
x' = -9 - √225 2*-4 = -9 - 15.0 -8 = -24.0 -8 = 3.0
x" = -9 + √225 2*-4 = -9 + 15.0 -8 = 6.0 -8 = -0.75
x' = 48.0
x" = -12.0
S = {x ∈ R / x' = 48.0, x" = -12.0 }