18x2 +19x -12 = 0
ax2 bx c = 0
a = 18
b = 19
c = -12
Δ = b2-4ac
Δ = 19² - (4 * 18 * -12)
Δ = 361 - (4*-216)
Δ = 361 - (-864)
Δ = 1225 Δ > 0
18x2+19x-12=0
x = -b ∓ √Δ 2a
x' = -19 - √1225 2*18 = -19 - 35.0 36 = -54.0 36 = -1.5
x" = -19 + √1225 2*18 = -19 + 35.0 36 = 16.0 36 = 0.444444444444
x' = -486.0
x" = 144.0
S = {x ∈ R / x' = -486.0, x" = 144.0 }