Let 1 and 2 be two solutions of Eq. (39.18) with energies E1 and E2, respectively, where

Let ψ1 and ψ2 be two solutions of Eq. (39.18) with energies E1 and E2, respectively, where E1 ≠ E2 Is ψ = Aψ1 + Bψ2, where A and B are nonzero constants, a solution to Eq. (39.18)? Explain your answer.