-1x2 -x +6 = 0

ax2 bx c = 0

a = -1

b = -1

c = 6

Δ = b2-4ac

Δ = -² - (4 * -1 * 6)

Δ = 1 - (4*-6)

Δ = 1 - (-24)

Δ = 25      Δ > 0

-x2-x+6=0

x = -b ∓ √Δ 2a

x' = 1 - √25 2*-1 = 1 - 5.0 -2 = -4.0 -2 = 2.0

x" = 1 + √25 2*-1 = 1 + 5.0 -2 = 6.0 -2 = -3.0

x' = 2.0

x" = -3.0

S = {x ∈ R / x' = 2.0, x" = -3.0 }