-15x2 -2x +8 = 0
ax2 bx c = 0
a = -15
b = -2
c = 8
Δ = b2-4ac
Δ = -2² - (4 * -15 * 8)
Δ = 4 - (4*-120)
Δ = 4 - (-480)
Δ = 484 Δ > 0
-15x2-2x+8=0
x = -b ∓ √Δ 2a
x' = 2 - √484 2*-15 = 2 - 22.0 -30 = -20.0 -30 = 0.666666666667
x" = 2 + √484 2*-15 = 2 + 22.0 -30 = 24.0 -30 = -0.8
x' = 150.0
x" = -180.0
S = {x ∈ R / x' = 150.0, x" = -180.0 }