The full relativistic expression for the cosmological redshift is z + 1 = √((c + v)/(c - v)) where v is the radial speed of the distant source.
(a) Show that in the non-relativistic limit the above approaches the expression z ≈ v/c
(b) A distant quasar is found at redshift z = 6. As a fraction of lightspeed c, calculate the speed at which this quasar appears to be receding from Earth.
(c) Another quasar has a much smaller redshift z = 0.023. Find how far away from Earth this quasar is.
You may use that the Hubble constant is H₀ = 69 km/(secMpc).