15x2 +14x +3 = 0
ax2 bx c = 0
a = 15
b = 14
c = 3
Δ = b2-4ac
Δ = 14² - (4 * 15 * 3)
Δ = 196 - (4*45)
Δ = 196 - (180)
Δ = 16 Δ > 0
15x2+14x+3=0
x = -b ∓ √Δ 2a
x' = -14 - √16 2*15 = -14 - 4.0 30 = -18.0 30 = -0.6
x" = -14 + √16 2*15 = -14 + 4.0 30 = -10.0 30 = -0.333333333333
x' = -135.0
x" = -75.0
S = {x ∈ R / x' = -135.0, x" = -75.0 }