Observation of eta' decays to pi+pi-pi0 and pi+pi-e+e-.

Using psi(2S)-->pi;{+}pi;{-}J/psi, J/psi-->gammaeta;{'} events acquired with the CLEO-c detector at the CESR e;{+}e;{-} collider, we make the first observations of the decays eta;{'}-->pi;{+}pi;{-}pi;{0} and eta;{'}-->pi;{+}pi;{-}e;{+}e;{-}, measuring absolute branching fractions (37_{-9};{+11}+/-4)x10;{-4} and (25_{-9};{+12}+/-5)x10;{-4}, respectively. For eta;{'}-->pi;{+}pi;{-}pi;{0}, this result probes the mechanism of isospin violation and the roles of pi;{0}/eta/eta;{'}-mixing and final state rescattering in strong decays. We also set upper limits on branching fractions for eta;{'} decays to pi;{+}pi;{-}micro;{+}micro;{-}, 2(pi;{+}pi;{-}), pi;{+}pi;{-}2pi;{0}, 2(pi;{+}pi;{-})pi;{0}, 3(pi;{+}pi;{-}), and invisible final states.