5x2 +6x -8 = 0
ax2 bx c = 0
a = 5
b = 6
c = -8
Δ = b2-4ac
Δ = 6² - (4 * 5 * -8)
Δ = 36 - (4*-40)
Δ = 36 - (-160)
Δ = 196 Δ > 0
5x2+6x-8=0
x = -b ∓ √Δ 2a
x' = -6 - √196 2*5 = -6 - 14.0 10 = -20.0 10 = -2.0
x" = -6 + √196 2*5 = -6 + 14.0 10 = 8.0 10 = 0.8
x' = -50.0
x" = 20.0
S = {x ∈ R / x' = -50.0, x" = 20.0 }