5x2 +14x +9 = 0
ax2 bx c = 0
a = 5
b = 14
c = 9
Δ = b2-4ac
Δ = 14² - (4 * 5 * 9)
Δ = 196 - (4*45)
Δ = 196 - (180)
Δ = 16 Δ > 0
5x2+14x+9=0
x = -b ∓ √Δ 2a
x' = -14 - √16 2*5 = -14 - 4.0 10 = -18.0 10 = -1.8
x" = -14 + √16 2*5 = -14 + 4.0 10 = -10.0 10 = -1.0
x' = -45.0
x" = -25.0
S = {x ∈ R / x' = -45.0, x" = -25.0 }