18x2 +4x -14 = 0
ax2 bx c = 0
a = 18
b = 4
c = -14
Δ = b2-4ac
Δ = 4² - (4 * 18 * -14)
Δ = 16 - (4*-252)
Δ = 16 - (-1008)
Δ = 1024 Δ > 0
18x2+4x-14=0
x = -b ∓ √Δ 2a
x' = -4 - √1024 2*18 = -4 - 32.0 36 = -36.0 36 = -1.0
x" = -4 + √1024 2*18 = -4 + 32.0 36 = 28.0 36 = 0.777777777778
x' = -324.0
x" = 252.0
S = {x ∈ R / x' = -324.0, x" = 252.0 }