Bêtifier is a french first group verb. So it follow the regular conjugation pattern of the first group like:
aimer.
Follow this link to see all the endings of the conjugation of the first group verbs :
conjugation rules and endings for the first group verbs.
However, although the terminations are perfectly regular, stem can be irregular and have numerous variations.
Bêtifier is conjugated the same way that verbs that end in :
-ier.
Bêtifier verb is conjugated in female form and in reflexive form. Be careful, the past participle of compound tenses must agree with the subject.