-6x2 +13x +15 = 0
ax2 bx c = 0
a = -6
b = 13
c = 15
Δ = b2-4ac
Δ = 13² - (4 * -6 * 15)
Δ = 169 - (4*-90)
Δ = 169 - (-360)
Δ = 529 Δ > 0
-6x2+13x+15=0
x = -b ∓ √Δ 2a
x' = -13 - √529 2*-6 = -13 - 23.0 -12 = -36.0 -12 = 3.0
x" = -13 + √529 2*-6 = -13 + 23.0 -12 = 10.0 -12 = -0.833333333333
x' = 108.0
x" = -30.0
S = {x ∈ R / x' = 108.0, x" = -30.0 }