18x2 +23x +5 = 0
ax2 bx c = 0
a = 18
b = 23
c = 5
Δ = b2-4ac
Δ = 23² - (4 * 18 * 5)
Δ = 529 - (4*90)
Δ = 529 - (360)
Δ = 169 Δ > 0
18x2+23x+5=0
x = -b ∓ √Δ 2a
x' = -23 - √169 2*18 = -23 - 13.0 36 = -36.0 36 = -1.0
x" = -23 + √169 2*18 = -23 + 13.0 36 = -10.0 36 = -0.277777777778
x' = -324.0
x" = -90.0
S = {x ∈ R / x' = -324.0, x" = -90.0 }