-4x2 +5x -1 = 0
ax2 bx c = 0
a = -4
b = 5
c = -1
Δ = b2-4ac
Δ = 5² - (4 * -4 * -1)
Δ = 25 - (4*4)
Δ = 25 - (16)
Δ = 9 Δ > 0
-4x2+5x-1=0
x = -b ∓ √Δ 2a
x' = -5 - √9 2*-4 = -5 - 3.0 -8 = -8.0 -8 = 1.0
x" = -5 + √9 2*-4 = -5 + 3.0 -8 = -2.0 -8 = 0.25
x' = 16.0
x" = 4.0
S = {x ∈ R / x' = 16.0, x" = 4.0 }