5x2 -18x +16 = 0
ax2 bx c = 0
a = 5
b = -18
c = 16
Δ = b2-4ac
Δ = -18² - (4 * 5 * 16)
Δ = 324 - (4*80)
Δ = 324 - (320)
Δ = 4 Δ > 0
5x2-18x+16=0
x = -b ∓ √Δ 2a
x' = 18 - √4 2*5 = 18 - 2.0 10 = 16.0 10 = 1.6
x" = 18 + √4 2*5 = 18 + 2.0 10 = 20.0 10 = 2.0
x' = 40.0
x" = 50.0
S = {x ∈ R / x' = 40.0, x" = 50.0 }