ðə nˈɛkst stˈɛp ɪz tə kənsˈɪdɚ ðɪ ᵻkwˈeɪʒən fɔːɹ jˈuː ˌʌndɚ smˈɔːl pɚɾɚbˈeɪʃənz fɹʌm pˈɜːfɛktli sˈɜːkjʊlɚɹ ˈɔːɹbɪts.
The next step is to consider the equation for u under small perturbations  from perfectly circular orbits.