-18x2 +22x -4 = 0
ax2 bx c = 0
a = -18
b = 22
c = -4
Δ = b2-4ac
Δ = 22² - (4 * -18 * -4)
Δ = 484 - (4*72)
Δ = 484 - (288)
Δ = 196 Δ > 0
-18x2+22x-4=0
x = -b ∓ √Δ 2a
x' = -22 - √196 2*-18 = -22 - 14.0 -36 = -36.0 -36 = 1.0
x" = -22 + √196 2*-18 = -22 + 14.0 -36 = -8.0 -36 = 0.222222222222
x' = 324.0
x" = 72.0
S = {x ∈ R / x' = 324.0, x" = 72.0 }