There were two mistakes in ¡­

There were two mistakes in problem 1 on problem set 2. The second order derivative should be with respect to t, not x, and below that it should be cos^3(t) rather than cos^3(x).

For psi0 and psi1, find only the particular solutions. Since we don't have boundary conditions, we ignore the homogeneous solutions.

Also: the sign on the RHS of equation 1 in problem 2 should be positive not negative.