-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 = -6.0 -2 = 3.0
x" = -1 + √25 2*-1 = -1 + 5.0 -2 = 4.0 -2 = -2.0
x' = 3.0
x" = -2.0
S = {x ∈ R / x' = 3.0, x" = -2.0 }