-18x2 -5x +13 = 0
ax2 bx c = 0
a = -18
b = -5
c = 13
Δ = b2-4ac
Δ = -5² - (4 * -18 * 13)
Δ = 25 - (4*-234)
Δ = 25 - (-936)
Δ = 961 Δ > 0
-18x2-5x+13=0
x = -b ∓ √Δ 2a
x' = 5 - √961 2*-18 = 5 - 31.0 -36 = -26.0 -36 = 0.722222222222
x" = 5 + √961 2*-18 = 5 + 31.0 -36 = 36.0 -36 = -1.0
x' = 234.0
x" = -324.0
S = {x ∈ R / x' = 234.0, x" = -324.0 }