-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 = 441 Δ > 0
-6x2-15x+9=0
x = -b ∓ √Δ 2a
x' = 15 - √441 2*-6 = 15 - 21.0 -12 = -6.0 -12 = 0.5
x" = 15 + √441 2*-6 = 15 + 21.0 -12 = 36.0 -12 = -3.0
x' = 18.0
x" = -108.0
S = {x ∈ R / x' = 18.0, x" = -108.0 }