-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 = -20.0 -30 = 0.666666666667
x" = -19 + √1 2*-15 = -19 + 1.0 -30 = -18.0 -30 = 0.6
x' = 150.0
x" = 135.0
S = {x ∈ R / x' = 150.0, x" = 135.0 }