15x2 -8x -12 = 0
ax2 bx c = 0
a = 15
b = -8
c = -12
Δ = b2-4ac
Δ = -8² - (4 * 15 * -12)
Δ = 64 - (4*-180)
Δ = 64 - (-720)
Δ = 784 Δ > 0
15x2-8x-12=0
x = -b ∓ √Δ 2a
x' = 8 - √784 2*15 = 8 - 28.0 30 = -20.0 30 = -0.666666666667
x" = 8 + √784 2*15 = 8 + 28.0 30 = 36.0 30 = 1.2
x' = -150.0
x" = 270.0
S = {x ∈ R / x' = -150.0, x" = 270.0 }