Consider looking at a similar question here:
In general, for technical subjects, number all equations even though you may not have referenced them in the text. It is almost always recommended that you do so, so that other people can refer to it easily and also so that any queries that are asked regarding it, can be directly done. For example, if you have two unnumbered equations and your reader has a question regarding one of them, there is no way for them to do so (they would have to be ambiguous...that equation that appears after this paragraph, which is something most of us would not like to do (and not preferable in an academic setting). So, in general, go ahead and number all of them.