-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 = -28.0 -8 = 3.5
x" = -12 + √256 2*-4 = -12 + 16.0 -8 = 4.0 -8 = -0.5
x' = 56.0
x" = -8.0
S = {x ∈ R / x' = 56.0, x" = -8.0 }