15x2 -13x -6 = 0
ax2 bx c = 0
a = 15
b = -13
c = -6
Δ = b2-4ac
Δ = -13² - (4 * 15 * -6)
Δ = 169 - (4*-90)
Δ = 169 - (-360)
Δ = 529 Δ > 0
15x2-13x-6=0
x = -b ∓ √Δ 2a
x' = 13 - √529 2*15 = 13 - 23.0 30 = -10.0 30 = -0.333333333333
x" = 13 + √529 2*15 = 13 + 23.0 30 = 36.0 30 = 1.2
x' = -75.0
x" = 270.0
S = {x ∈ R / x' = -75.0, x" = 270.0 }