1. The problem statement, all variables and given/known data With knowledge of the orthogonality conditions for eigenfunctions with discrete eigenvalues, determine the orthonormal set for eigenfunctions with continuous eigenvalues. Use the definition of completeness to show that | a(k) |^2 = 1. 2. The attempt at a solution The first step is: Since the integral is only equal to 0 when k' = k. (The same condition as the kronecker delta.) Next: After here I get a bit lost, even though I think this is almost the solution. My work differs from the course notes and a QM book I've looked through. They both have an integration with respect to k for the RHS, not x. Any pointers would be greatly appreciated.