5x2 +18x +16 = 0
ax2 bx c = 0
a = 5
b = 18
c = 16
Δ = b2-4ac
Δ = 18² - (4 * 5 * 16)
Δ = 324 - (4*80)
Δ = 324 - (320)
Δ = 4 Δ > 0
5x2+18x+16=0
x = -b ∓ √Δ 2a
x' = -18 - √4 2*5 = -18 - 2.0 10 = -20.0 10 = -2.0
x" = -18 + √4 2*5 = -18 + 2.0 10 = -16.0 10 = -1.6
x' = -50.0
x" = -40.0
S = {x ∈ R / x' = -50.0, x" = -40.0 }