-15x2 -6x +9 = 0
ax2 bx c = 0
a = -15
b = -6
c = 9
Δ = b2-4ac
Δ = -6² - (4 * -15 * 9)
Δ = 36 - (4*-135)
Δ = 36 - (-540)
Δ = 576 Δ > 0
-15x2-6x+9=0
x = -b ∓ √Δ 2a
x' = 6 - √576 2*-15 = 6 - 24.0 -30 = -18.0 -30 = 0.6
x" = 6 + √576 2*-15 = 6 + 24.0 -30 = 30.0 -30 = -1.0
x' = 135.0
x" = -225.0
S = {x ∈ R / x' = 135.0, x" = -225.0 }