18x2 +10x -8 = 0
ax2 bx c = 0
a = 18
b = 10
c = -8
Δ = b2-4ac
Δ = 10² - (4 * 18 * -8)
Δ = 100 - (4*-144)
Δ = 100 - (-576)
Δ = 676 Δ > 0
18x2+10x-8=0
x = -b ∓ √Δ 2a
x' = -10 - √676 2*18 = -10 - 26.0 36 = -36.0 36 = -1.0
x" = -10 + √676 2*18 = -10 + 26.0 36 = 16.0 36 = 0.444444444444
x' = -324.0
x" = 144.0
S = {x ∈ R / x' = -324.0, x" = 144.0 }