5x2 +13x +8 = 0
ax2 bx c = 0
a = 5
b = 13
c = 8
Δ = b2-4ac
Δ = 13² - (4 * 5 * 8)
Δ = 169 - (4*40)
Δ = 169 - (160)
Δ = 9 Δ > 0
5x2+13x+8=0
x = -b ∓ √Δ 2a
x' = -13 - √9 2*5 = -13 - 3.0 10 = -16.0 10 = -1.6
x" = -13 + √9 2*5 = -13 + 3.0 10 = -10.0 10 = -1.0
x' = -40.0
x" = -25.0
S = {x ∈ R / x' = -40.0, x" = -25.0 }