Wo states | φ 1 ⟩ and | φ 2 ⟩ are stationary states with energy eigenvalues e1 and e2. their position-space representations are φ 1 ( x ) and φ 2 ( x ). let a state at time t = 0 be given by | ψ ( 0 ) ⟩ = 1 2 ( | φ 1 ⟩ + | φ 2 ⟩ ). write the position-space representation for | ψ ( t ) ⟩.