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 = -36.0 30 = -1.2
x" = -8 + √784 2*15 = -8 + 28.0 30 = 20.0 30 = 0.666666666667
x' = -270.0
x" = 150.0
S = {x ∈ R / x' = -270.0, x" = 150.0 }