5x2 +14x +8 = 0
ax2 bx c = 0
a = 5
b = 14
c = 8
Δ = b2-4ac
Δ = 14² - (4 * 5 * 8)
Δ = 196 - (4*40)
Δ = 196 - (160)
Δ = 36 Δ > 0
5x2+14x+8=0
x = -b ∓ √Δ 2a
x' = -14 - √36 2*5 = -14 - 6.0 10 = -20.0 10 = -2.0
x" = -14 + √36 2*5 = -14 + 6.0 10 = -8.0 10 = -0.8
x' = -50.0
x" = -20.0
S = {x ∈ R / x' = -50.0, x" = -20.0 }