15x2 -12x -3 = 0
ax2 bx c = 0
a = 15
b = -12
c = -3
Δ = b2-4ac
Δ = -12² - (4 * 15 * -3)
Δ = 144 - (4*-45)
Δ = 144 - (-180)
Δ = 324 Δ > 0
15x2-12x-3=0
x = -b ∓ √Δ 2a
x' = 12 - √324 2*15 = 12 - 18.0 30 = -6.0 30 = -0.2
x" = 12 + √324 2*15 = 12 + 18.0 30 = 30.0 30 = 1.0
x' = -45.0
x" = 225.0
S = {x ∈ R / x' = -45.0, x" = 225.0 }