-1x2 +8x -12 = 0
ax2 bx c = 0
a = -1
b = 8
c = -12
Δ = b2-4ac
Δ = 8² - (4 * -1 * -12)
Δ = 64 - (4*12)
Δ = 64 - (48)
Δ = 16 Δ > 0
-x2+8x-12=0
x = -b ∓ √Δ 2a
x' = -8 - √16 2*-1 = -8 - 4.0 -2 = -12.0 -2 = 6.0
x" = -8 + √16 2*-1 = -8 + 4.0 -2 = -4.0 -2 = 2.0
x' = 6.0
x" = 2.0
S = {x ∈ R / x' = 6.0, x" = 2.0 }