Let p(x) be a cubic polynomial with rational coefficients. q1, q2, q3, ... is a sequence of rationals such that q_n \equal{} p(q_{n \plus{} 1}) for all positive n. Show that for some k, we have q_{n \plus{} k} \equal{} q_n for all positive n. algebrapolynomialnumber theoryCubicIterationIMO Shortlist