18x2 +23x +7 = 0
ax2 bx c = 0
a = 18
b = 23
c = 7
Δ = b2-4ac
Δ = 23² - (4 * 18 * 7)
Δ = 529 - (4*126)
Δ = 529 - (504)
Δ = 25 Δ > 0
18x2+23x+7=0
x = -b ∓ √Δ 2a
x' = -23 - √25 2*18 = -23 - 5.0 36 = -28.0 36 = -0.777777777778
x" = -23 + √25 2*18 = -23 + 5.0 36 = -18.0 36 = -0.5
x' = -252.0
x" = -162.0
S = {x ∈ R / x' = -252.0, x" = -162.0 }