18x2 -17x -1 = 0
ax2 bx c = 0
a = 18
b = -17
c = -1
Δ = b2-4ac
Δ = -17² - (4 * 18 * -1)
Δ = 289 - (4*-18)
Δ = 289 - (-72)
Δ = 361 Δ > 0
18x2-17x-1=0
x = -b ∓ √Δ 2a
x' = 17 - √361 2*18 = 17 - 19.0 36 = -2.0 36 = -0.0555555555556
x" = 17 + √361 2*18 = 17 + 19.0 36 = 36.0 36 = 1.0
x' = -18.0
x" = 324.0
S = {x ∈ R / x' = -18.0, x" = 324.0 }