-18x2 -17x -4 = 0
ax2 bx c = 0
a = -18
b = -17
c = -4
Δ = b2-4ac
Δ = -17² - (4 * -18 * -4)
Δ = 289 - (4*72)
Δ = 289 - (288)
Δ = 1 Δ > 0
-18x2-17x-4=0
x = -b ∓ √Δ 2a
x' = 17 - √1 2*-18 = 17 - 1.0 -36 = 16.0 -36 = -0.444444444444
x" = 17 + √1 2*-18 = 17 + 1.0 -36 = 18.0 -36 = -0.5
x' = -144.0
x" = -162.0
S = {x ∈ R / x' = -144.0, x" = -162.0 }