5x2 -14x +8 = 0
ax2 bx c = 0
a = 5
b = -14
c = 8
Δ = b2-4ac
Δ = -14² - (4 * 5 * 8)
Δ = 196 - (4*40)
Δ = 196 - (160)
Δ = 36 Δ > 0
5x2-14x+8=0
x = -b ∓ √Δ 2a
x' = 14 - √36 2*5 = 14 - 6.0 10 = 8.0 10 = 0.8
x" = 14 + √36 2*5 = 14 + 6.0 10 = 20.0 10 = 2.0
x' = 20.0
x" = 50.0
S = {x ∈ R / x' = 20.0, x" = 50.0 }