-1x2 +5x +14 = 0
ax2 bx c = 0
a = -1
b = 5
c = 14
Δ = b2-4ac
Δ = 5² - (4 * -1 * 14)
Δ = 25 - (4*-14)
Δ = 25 - (-56)
Δ = 81 Δ > 0
-x2+5x+14=0
x = -b ∓ √Δ 2a
x' = -5 - √81 2*-1 = -5 - 9.0 -2 = -14.0 -2 = 7.0
x" = -5 + √81 2*-1 = -5 + 9.0 -2 = 4.0 -2 = -2.0
x' = 7.0
x" = -2.0
S = {x ∈ R / x' = 7.0, x" = -2.0 }