A tanár szerint a válasz helyes.

Because a is the Hungarian definite article, meaning the.

• a tanár = the teacher
• a válasz = the answer

Hungarian uses the definite article much like English does, although article usage is not always identical in the two languages.

Also, a changes to az before a vowel sound:

• a tanár
• az ember

Szerint means according to, in the opinion of, or by the view/judgment of.

So:

• A tanár szerint = according to the teacher

It is very common in Hungarian for reporting someone’s opinion:

• Péter szerint ez jó. = According to Péter, this is good.
• Az orvos szerint pihenni kell. = According to the doctor, one must rest.

Because szerint is a postposition, and it normally follows a noun in its basic form.

So you say:

• a tanár szerint
• Péter szerint
• a könyv szerint

Unlike English prepositions, Hungarian postpositions come after the noun, not before it.

So English:

• according to the teacher

Hungarian:

• the teacher according to → a tanár szerint

In Hungarian, the verb to be is often omitted in the present tense, third person singular and plural, when it links a subject to a noun or adjective.

So:

• A válasz helyes. = The answer is correct.

There is no separate word for is here.

Compare:

• Én fáradt vagyok. = I am tired.
• Te fáradt vagy. = You are tired.
• Ő fáradt. = He/She is tired. ← no van

This is one of the most important patterns in Hungarian.

Because helyes is acting as a predicate adjective, not as an attributive adjective.

Compare the two patterns:

• a helyes válasz = the correct answer
  Here, helyes comes before the noun because it directly describes it.

• a válasz helyes = the answer is correct
  Here, helyes comes after the noun because it is part of the predicate.

So in your sentence, the structure is:

• a válasz = subject
• helyes = predicate adjective

Yes. That is also natural Hungarian.

Both are possible:

• A tanár szerint a válasz helyes.
• A tanár szerint helyes a válasz.

The basic meaning stays the same, but the word order can slightly shift the focus.

A very rough way to think about it:

• a válasz helyes gives a more neutral the answer is correct
• helyes a válasz can put a bit more attention on correct

Hungarian word order is flexible, and it often reflects emphasis, topic, and focus more than strict grammatical necessity.

Not exactly.

• helyes = correct, right, accurate
• jó = good

So:

• A válasz helyes. = The answer is correct.
• A válasz jó. = The answer is good.

In many contexts, helyes is the more precise word for an answer on a test, in class, or in a factual discussion.

No. Szerint can be used with people, books, rules, plans, maps, and many other things.

Examples:

• A tanár szerint... = According to the teacher...
• A könyv szerint... = According to the book...
• A szabályok szerint... = According to the rules...
• A terv szerint... = According to the plan...

So it is a very general word.

Because the sentence has the definite article a:

• a tanár = the teacher

If you wanted a teacher, Hungarian would use egy:

• egy tanár = a teacher

So the sentence specifically refers to some identifiable teacher, not just any teacher.

In normal standard Hungarian, that would usually sound incomplete or unnatural.

Hungarian generally wants an article here:

• A tanár szerint a válasz helyes.

Without the article, it might only appear in special contexts such as notes, headlines, or very compressed style, but it is not the normal full sentence a learner should copy.

The sentence can be divided like this:

• A tanár szerint = according to the teacher
• a válasz helyes = the answer is correct

So the overall structure is:

[opinion source] + [statement]

More literally:

• the teacher according to, the answer correct

Natural English:

• According to the teacher, the answer is correct.

This is a very common Hungarian pattern:

• X szerint, Y ilyen/olyan.
• According to X, Y is like this/that.