-4x2 +16x -7 = 0
ax2 bx c = 0
a = -4
b = 16
c = -7
Δ = b2-4ac
Δ = 16² - (4 * -4 * -7)
Δ = 256 - (4*28)
Δ = 256 - (112)
Δ = 144 Δ > 0
-4x2+16x-7=0
x = -b ∓ √Δ 2a
x' = -16 - √144 2*-4 = -16 - 12.0 -8 = -28.0 -8 = 3.5
x" = -16 + √144 2*-4 = -16 + 12.0 -8 = -4.0 -8 = 0.5
x' = 56.0
x" = 8.0
S = {x ∈ R / x' = 56.0, x" = 8.0 }