-18x2 +17x -4 = 0
ax2 bx c = 0
a = -18
b = 17
c = -4
Δ = b2-4ac
Δ = 17² - (4 * -18 * -4)
Δ = 289 - (4*72)
Δ = 289 - (288)
Δ = 1 Δ > 0
-18x2+17x-4=0
x = -b ∓ √Δ 2a
x' = -17 - √1 2*-18 = -17 - 1.0 -36 = -18.0 -36 = 0.5
x" = -17 + √1 2*-18 = -17 + 1.0 -36 = -16.0 -36 = 0.444444444444
x' = 162.0
x" = 144.0
S = {x ∈ R / x' = 162.0, x" = 144.0 }