18x2 -7x -11 = 0
ax2 bx c = 0
a = 18
b = -7
c = -11
Δ = b2-4ac
Δ = -7² - (4 * 18 * -11)
Δ = 49 - (4*-198)
Δ = 49 - (-792)
Δ = 841 Δ > 0
18x2-7x-11=0
x = -b ∓ √Δ 2a
x' = 7 - √841 2*18 = 7 - 29.0 36 = -22.0 36 = -0.611111111111
x" = 7 + √841 2*18 = 7 + 29.0 36 = 36.0 36 = 1.0
x' = -198.0
x" = 324.0
S = {x ∈ R / x' = -198.0, x" = 324.0 }