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 = -36.0 30 = -1.2
x" = -13 + √529 2*15 = -13 + 23.0 30 = 10.0 30 = 0.333333333333
x' = -270.0
x" = 75.0
S = {x ∈ R / x' = -270.0, x" = 75.0 }