18x2 +11x +1 = 0
ax2 bx c = 0
a = 18
b = 11
c = 1
Δ = b2-4ac
Δ = 11² - (4 * 18 * 1)
Δ = 121 - (4*18)
Δ = 121 - (72)
Δ = 49 Δ > 0
18x2+11x+1=0
x = -b ∓ √Δ 2a
x' = -11 - √49 2*18 = -11 - 7.0 36 = -18.0 36 = -0.5
x" = -11 + √49 2*18 = -11 + 7.0 36 = -4.0 36 = -0.111111111111
x' = -162.0
x" = -36.0
S = {x ∈ R / x' = -162.0, x" = -36.0 }