A one-electron atom whose ground state is nondegenerate is placed in a uniform electric field in the z-direction. Obtain an approximate expression for the induced electric dipole moment of the ground state by considering the expectation value of ez with respect to the perturbed-state vector computed to first order. Show that the same expression can also be obtained from the energy shift Δ = - α|E|²/2 of the ground state computed to second order. Ignore spin.