-6x2 +13x +5 = 0
ax2 bx c = 0
a = -6
b = 13
c = 5
Δ = b2-4ac
Δ = 13² - (4 * -6 * 5)
Δ = 169 - (4*-30)
Δ = 169 - (-120)
Δ = 289 Δ > 0
-6x2+13x+5=0
x = -b ∓ √Δ 2a
x' = -13 - √289 2*-6 = -13 - 17.0 -12 = -30.0 -12 = 2.5
x" = -13 + √289 2*-6 = -13 + 17.0 -12 = 4.0 -12 = -0.333333333333
x' = 90.0
x" = -12.0
S = {x ∈ R / x' = 90.0, x" = -12.0 }