5x2 +19x +12 = 0
ax2 bx c = 0
a = 5
b = 19
c = 12
Δ = b2-4ac
Δ = 19² - (4 * 5 * 12)
Δ = 361 - (4*60)
Δ = 361 - (240)
Δ = 121 Δ > 0
5x2+19x+12=0
x = -b ∓ √Δ 2a
x' = -19 - √121 2*5 = -19 - 11.0 10 = -30.0 10 = -3.0
x" = -19 + √121 2*5 = -19 + 11.0 10 = -8.0 10 = -0.8
x' = -75.0
x" = -20.0
S = {x ∈ R / x' = -75.0, x" = -20.0 }