-18x2 -5x +23 = 0
ax2 bx c = 0
a = -18
b = -5
c = 23
Δ = b2-4ac
Δ = -5² - (4 * -18 * 23)
Δ = 25 - (4*-414)
Δ = 25 - (-1656)
Δ = 1681 Δ > 0
-18x2-5x+23=0
x = -b ∓ √Δ 2a
x' = 5 - √1681 2*-18 = 5 - 41.0 -36 = -36.0 -36 = 1.0
x" = 5 + √1681 2*-18 = 5 + 41.0 -36 = 46.0 -36 = -1.27777777778
x' = 324.0
x" = -414.0
S = {x ∈ R / x' = 324.0, x" = -414.0 }