-4x2 -12x +7 = 0
ax2 bx c = 0
a = -4
b = -12
c = 7
Δ = b2-4ac
Δ = -12² - (4 * -4 * 7)
Δ = 144 - (4*-28)
Δ = 144 - (-112)
Δ = 256 Δ > 0
-4x2-12x+7=0
x = -b ∓ √Δ 2a
x' = 12 - √256 2*-4 = 12 - 16.0 -8 = -4.0 -8 = 0.5
x" = 12 + √256 2*-4 = 12 + 16.0 -8 = 28.0 -8 = -3.5
x' = 8.0
x" = -56.0
S = {x ∈ R / x' = 8.0, x" = -56.0 }