-6x2 -15x -9 = 0
ax2 bx c = 0
a = -6
b = -15
c = -9
Δ = b2-4ac
Δ = -15² - (4 * -6 * -9)
Δ = 225 - (4*54)
Δ = 225 - (216)
Δ = 9 Δ > 0
-6x2-15x-9=0
x = -b ∓ √Δ 2a
x' = 15 - √9 2*-6 = 15 - 3.0 -12 = 12.0 -12 = -1.0
x" = 15 + √9 2*-6 = 15 + 3.0 -12 = 18.0 -12 = -1.5
x' = -36.0
x" = -54.0
S = {x ∈ R / x' = -36.0, x" = -54.0 }