-1x2 +6x -8 = 0
ax2 bx c = 0
a = -1
b = 6
c = -8
Δ = b2-4ac
Δ = 6² - (4 * -1 * -8)
Δ = 36 - (4*8)
Δ = 36 - (32)
Δ = 4 Δ > 0
-x2+6x-8=0
x = -b ∓ √Δ 2a
x' = -6 - √4 2*-1 = -6 - 2.0 -2 = -8.0 -2 = 4.0
x" = -6 + √4 2*-1 = -6 + 2.0 -2 = -4.0 -2 = 2.0
x' = 4.0
x" = 2.0
S = {x ∈ R / x' = 4.0, x" = 2.0 }