"We are not mathematicians."
Translation:Chúng tôi không phải là các nhà toán học.
You use "không phải" when:
You're using "là"; example: this sentence.
You mean "do(es)n't have to (do sth)"; example: "Tôi không phải làm bài tập." (I don't have to do homework)
Put it at the beginning of the sentence; example: "Không phải tôi làm chuyện này." (It wasn't* me who did this) (The logic is basically the same as 1st case, but it is used without là).
im confused about whether or not i can say chúng tôi or chúng ta. i think chúng tôi means we excluding the person the speaker is talking you and chúng ta(probably spelled wrong) is said to include the speaker, the listener and the third party. i got this info from somebody else in the comments a few questions before this and am at a loss for the actual meaning.