15x2 +18x +3 = 0
ax2 bx c = 0
a = 15
b = 18
c = 3
Δ = b2-4ac
Δ = 18² - (4 * 15 * 3)
Δ = 324 - (4*45)
Δ = 324 - (180)
Δ = 144 Δ > 0
15x2+18x+3=0
x = -b ∓ √Δ 2a
x' = -18 - √144 2*15 = -18 - 12.0 30 = -30.0 30 = -1.0
x" = -18 + √144 2*15 = -18 + 12.0 30 = -6.0 30 = -0.2
x' = -225.0
x" = -45.0
S = {x ∈ R / x' = -225.0, x" = -45.0 }