Starting with Eq. 9.170, calculate the group velocity, assuming there is only one resonance, at ω0. Use a computer to graph y≡vg/c as a function of x≡(ω/ω0)2, from x=0 to 2, (a) for γ=0, and (b) for γ=(0.1)ω0. Let (Nq2)/(2mϵ0ω02)=0.003. Note that the group velocity can exceed c.