-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 }