-1x2 +5x +6 = 0
ax2 bx c = 0
a = -1
b = 5
c = 6
Δ = b2-4ac
Δ = 5² - (4 * -1 * 6)
Δ = 25 - (4*-6)
Δ = 25 - (-24)
Δ = 49 Δ > 0
-x2+5x+6=0
x = -b ∓ √Δ 2a
x' = -5 - √49 2*-1 = -5 - 7.0 -2 = -12.0 -2 = 6.0
x" = -5 + √49 2*-1 = -5 + 7.0 -2 = 2.0 -2 = -1.0
x' = 6.0
x" = -1.0
S = {x ∈ R / x' = 6.0, x" = -1.0 }