-18x2 -2x +20 = 0
ax2 bx c = 0
a = -18
b = -2
c = 20
Δ = b2-4ac
Δ = -2² - (4 * -18 * 20)
Δ = 4 - (4*-360)
Δ = 4 - (-1440)
Δ = 1444 Δ > 0
-18x2-2x+20=0
x = -b ∓ √Δ 2a
x' = 2 - √1444 2*-18 = 2 - 38.0 -36 = -36.0 -36 = 1.0
x" = 2 + √1444 2*-18 = 2 + 38.0 -36 = 40.0 -36 = -1.11111111111
x' = 324.0
x" = -360.0
S = {x ∈ R / x' = 324.0, x" = -360.0 }