-18x2 -7x +1 = 0
ax2 bx c = 0
a = -18
b = -7
c = 1
Δ = b2-4ac
Δ = -7² - (4 * -18 * 1)
Δ = 49 - (4*-18)
Δ = 49 - (-72)
Δ = 121 Δ > 0
-18x2-7x+1=0
x = -b ∓ √Δ 2a
x' = 7 - √121 2*-18 = 7 - 11.0 -36 = -4.0 -36 = 0.111111111111
x" = 7 + √121 2*-18 = 7 + 11.0 -36 = 18.0 -36 = -0.5
x' = 36.0
x" = -162.0
S = {x ∈ R / x' = 36.0, x" = -162.0 }