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 = -30.0 30 = -1.0
x" = -3 + √729 2*15 = -3 + 27.0 30 = 24.0 30 = 0.8
x' = -225.0
x" = 180.0
S = {x ∈ R / x' = -225.0, x" = 180.0 }