why won't we ask a question, where are you live?

It should be: where do you live?

Because we never use "be forms" (am, is, are, was, were) with Main verbs(v1). Be forms takes either v1 + ing form or v3 in present tense. Ex..Where are you going ? How is it done ? Your sentence, "where are you live ?" is wrong because be form(are) is used with verb1 (live) which is wrong grammatically. We can rewrite this sentence correctly as: Where are you living now ?

For simple way..... The question which lies "verb" start questions with Do/Does 1) where do you live? 2)does he speak? Questions without "verb" starts with am/is/are 1)am I raju? 2)are they coming? 3) is he going?