-18x2 +19x -5 = 0
ax2 bx c = 0
a = -18
b = 19
c = -5
Δ = b2-4ac
Δ = 19² - (4 * -18 * -5)
Δ = 361 - (4*90)
Δ = 361 - (360)
Δ = 1 Δ > 0
-18x2+19x-5=0
x = -b ∓ √Δ 2a
x' = -19 - √1 2*-18 = -19 - 1.0 -36 = -20.0 -36 = 0.555555555556
x" = -19 + √1 2*-18 = -19 + 1.0 -36 = -18.0 -36 = 0.5
x' = 180.0
x" = 162.0
S = {x ∈ R / x' = 180.0, x" = 162.0 }