The cubic polynomial is (x-1)(x-(-1/2 + a))(x-(-1/2 - a))
roots are centered at the origin
first three critical points of Newton's method are the roots
last critical point is at 0.
The large-scale parameter picture obtained by plotting rate of attraction of 0 to 3 roots.
First Blowup "The Mandelbrain"
Second Blowup
J-set corresponding to the baby mandelbroty in the above
Blowup of J-set