-12x2 +15x +18 = 0
ax2 bx c = 0
a = -12
b = 15
c = 18
Δ = b2-4ac
Δ = 15² - (4 * -12 * 18)
Δ = 225 - (4*-216)
Δ = 225 - (-864)
Δ = 1089 Δ > 0
-12x2+15x+18=0
x = -b ∓ √Δ 2a
x' = -15 - √1089 2*-12 = -15 - 33.0 -24 = -48.0 -24 = 2.0
x" = -15 + √1089 2*-12 = -15 + 33.0 -24 = 18.0 -24 = -0.75
x' = 288.0
x" = -108.0
S = {x ∈ R / x' = 288.0, x" = -108.0 }