Given the following:
If I were to use the power rule, I would do:
Substituting back into the original equation, it is correct. However, there is a missed answer:
Substituting that into the original equation, it is correct as well, but while using the power rule, it has been overlooked.
Obviously, this is a rather simple question, so I could have just done $3^2=(x^2-3)^2$ and solved it like that, in which case the answer of $0$ would appear. However, for more complicated questions, how would one go about doing it? And are there exceptions to this exception?