I need help determining if the following statement is mathematically valid, where psi_0 and psi_1 are the first two stationary states of the SHO: http://af10.mail.ru/cgi-bin/readmsg?id=13807553990000000798;0;1&mode=attachment&bs=2783&bl=281383&ct=image%2fjpeg&cn=mms_picture.jpeg&cte=base64 Basically what I did was cancel the dx's as if it was algebraic equation, and then since my integration became wrt psi_1, I changed my limits from 0->0, since at +/- infinity, psi_1 must be zero. And of course if your limits of integration are same, result must be zero. Specifically, I would like to know where exactly (at which of my above steps) is the flaw? (there must be a flaw since I do not get correct solution when I use this to calculate other stuff...this integral should in fact not be zero). If I replace psi_1 by psi_0, for example, then I think this is correct, since I did it on my recent QM test and got full credit. Any help with this is appreciated! Any help is appreciated!