a(x)=x^{2}

f_{k}(x)= \frac{ 4x^{3}+kx-k^{3} }{ 4x} 

Ang11/08

k = -2 (slider from -5 to 5, step 1)
f(x) = (4 x^(3) + k x - k^(3)) / (4 x)
e(x) = 3 x^(2) - 0.5 x
a(x) = x^(2)