18x2 +15x -12 = 0
ax2 bx c = 0
a = 18
b = 15
c = -12
Δ = b2-4ac
Δ = 15² - (4 * 18 * -12)
Δ = 225 - (4*-216)
Δ = 225 - (-864)
Δ = 1089 Δ > 0
18x2+15x-12=0
x = -b ∓ √Δ 2a
x' = -15 - √1089 2*18 = -15 - 33.0 36 = -48.0 36 = -1.33333333333
x" = -15 + √1089 2*18 = -15 + 33.0 36 = 18.0 36 = 0.5
x' = -432.0
x" = 162.0
S = {x ∈ R / x' = -432.0, x" = 162.0 }