Two balls with masses M and m are connected

Two balls with masses M and m are connected by a rigid rod of length L and negligible mass as in Figure P10.22. For an axis perpendicular to the rod, show that the system has the minimum moment of inertia when the axis passes through the center of mass, Show that this moment of inertia is I = ÂľL2, where 7 = mM/(m + M).