-4x2 -15x -14 = 0
ax2 bx c = 0
a = -4
b = -15
c = -14
Δ = b2-4ac
Δ = -15² - (4 * -4 * -14)
Δ = 225 - (4*56)
Δ = 225 - (224)
Δ = 1 Δ > 0
-4x2-15x-14=0
x = -b ∓ √Δ 2a
x' = 15 - √1 2*-4 = 15 - 1.0 -8 = 14.0 -8 = -1.75
x" = 15 + √1 2*-4 = 15 + 1.0 -8 = 16.0 -8 = -2.0
x' = -28.0
x" = -32.0
S = {x ∈ R / x' = -28.0, x" = -32.0 }