-15x2 -19x -6 = 0
ax2 bx c = 0
a = -15
b = -19
c = -6
Δ = b2-4ac
Δ = -19² - (4 * -15 * -6)
Δ = 361 - (4*90)
Δ = 361 - (360)
Δ = 1 Δ > 0
-15x2-19x-6=0
x = -b ∓ √Δ 2a
x' = 19 - √1 2*-15 = 19 - 1.0 -30 = 18.0 -30 = -0.6
x" = 19 + √1 2*-15 = 19 + 1.0 -30 = 20.0 -30 = -0.666666666667
x' = -135.0
x" = -150.0
S = {x ∈ R / x' = -135.0, x" = -150.0 }