-1x2 -9x -14 = 0
ax2 bx c = 0
a = -1
b = -9
c = -14
Δ = b2-4ac
Δ = -9² - (4 * -1 * -14)
Δ = 81 - (4*14)
Δ = 81 - (56)
Δ = 25 Δ > 0
-x2-9x-14=0
x = -b ∓ √Δ 2a
x' = 9 - √25 2*-1 = 9 - 5.0 -2 = 4.0 -2 = -2.0
x" = 9 + √25 2*-1 = 9 + 5.0 -2 = 14.0 -2 = -7.0
x' = -2.0
x" = -7.0
S = {x ∈ R / x' = -2.0, x" = -7.0 }