Discuss the motion of a particle in a central inverse-square-law force field for a superimposed force whose magnitude is inversely proportional to the cube of the distance from the particle to the force center; that is,
F(r)=−r2k−r3λk,λ>0
Show that the motion is described by a precessing ellipse. Consider the cases λ<l2/μ, λ=l2/μ, and λ>l2/μ.