15x2 -3x -12 = 0
ax2 bx c = 0
a = 15
b = -3
c = -12
Δ = b2-4ac
Δ = -3² - (4 * 15 * -12)
Δ = 9 - (4*-180)
Δ = 9 - (-720)
Δ = 729 Δ > 0
15x2-3x-12=0
x = -b ∓ √Δ 2a
x' = 3 - √729 2*15 = 3 - 27.0 30 = -24.0 30 = -0.8
x" = 3 + √729 2*15 = 3 + 27.0 30 = 30.0 30 = 1.0
x' = -180.0
x" = 225.0
S = {x ∈ R / x' = -180.0, x" = 225.0 }