5x2 +8x +3 = 0
ax2 bx c = 0
a = 5
b = 8
c = 3
Δ = b2-4ac
Δ = 8² - (4 * 5 * 3)
Δ = 64 - (4*15)
Δ = 64 - (60)
Δ = 4 Δ > 0
5x2+8x+3=0
x = -b ∓ √Δ 2a
x' = -8 - √4 2*5 = -8 - 2.0 10 = -10.0 10 = -1.0
x" = -8 + √4 2*5 = -8 + 2.0 10 = -6.0 10 = -0.6
x' = -25.0
x" = -15.0
S = {x ∈ R / x' = -25.0, x" = -15.0 }