5x2 +23x +12 = 0
ax2 bx c = 0
a = 5
b = 23
c = 12
Δ = b2-4ac
Δ = 23² - (4 * 5 * 12)
Δ = 529 - (4*60)
Δ = 529 - (240)
Δ = 289 Δ > 0
5x2+23x+12=0
x = -b ∓ √Δ 2a
x' = -23 - √289 2*5 = -23 - 17.0 10 = -40.0 10 = -4.0
x" = -23 + √289 2*5 = -23 + 17.0 10 = -6.0 10 = -0.6
x' = -100.0
x" = -15.0
S = {x ∈ R / x' = -100.0, x" = -15.0 }