= 3 0 a - Let p(x) = x+ + 2x4 + x + xo be a Poincare' Map for a certain differential equation x' (t) = f(t, x), where f(t, x) is a periodic function in t variable with period T. The this differential equation admits a periodic solution if the initial condition(s) is/are 20 = -1 20 0 X0 = 0, X0 = +1 Xo 0 and Xo = -1 None