5x2 +8x -4 = 0
ax2 bx c = 0
a = 5
b = 8
c = -4
Δ = b2-4ac
Δ = 8² - (4 * 5 * -4)
Δ = 64 - (4*-20)
Δ = 64 - (-80)
Δ = 144 Δ > 0
5x2+8x-4=0
x = -b ∓ √Δ 2a
x' = -8 - √144 2*5 = -8 - 12.0 10 = -20.0 10 = -2.0
x" = -8 + √144 2*5 = -8 + 12.0 10 = 4.0 10 = 0.4
x' = -50.0
x" = 10.0
S = {x ∈ R / x' = -50.0, x" = 10.0 }