Learn Hardcore Greek: Ο φοιτητής και η φοιτήτρια ρωτάνε τον καθηγητή αν αυτή η λύση είναι η πιο απλή. - The male student and the female student ask the professor if this solution is the simplest.

Greek articles change form according to gender (masc./fem./neut.), number (sing./pl.), and case (nominative, genitive, accusative, etc.), unlike English the, which never changes.

What is the difference between φοιτητής and φοιτήτρια?

They are the masculine and feminine forms of the same noun:

φοιτητής = male university student
φοιτήτρια = female university student

Typical pattern:

masculine: -τής → φοιτητής
feminine: -τρια → φοιτήτρια

Plural forms:

οι φοιτητές = the (male / mixed group) students
οι φοιτήτριες = the female students

Also, φοιτητής/φοιτήτρια is specifically for university students. For school pupils you’d usually see μαθητής / μαθήτρια.

Why is the verb ρωτάνε plural? Could it be ρωτά instead?

The subject is Ο φοιτητής και η φοιτήτρια – that’s two people, so the subject is plural.
The verb must agree:

ρωτάει / ρωτά = he/she asks (3rd person singular)
ρωτάνε / ρωτούν(ε) = they ask (3rd person plural)

So here:

Ο φοιτητής και η φοιτήτρια ρωτάνε…
“The (male) student and the (female) student ask…”

Using ρωτά would be ungrammatical because it’s singular while the subject is plural.

Is there any difference between ρωτάνε and ρωτούν(ε)?

They are both 3rd person plural present tense of ρωτάω / ρωτώ (“to ask”).

ρωτάνε – more colloquial, very common in everyday speech
ρωτούν – a bit more formal or written style
ρωτούνε – also heard in speech, similar to ρωτάνε

In your sentence, you could also say:

Ο φοιτητής και η φοιτήτρια ρωτούν τον καθηγητή…

It would sound slightly more formal, but both are correct.

Why is it τον καθηγητή and not ο καθηγητής?

ο καθηγητής is nominative (used for the subject of the sentence).
Here, τον καθηγητή is the object of the verb ρωτάνε (“they ask whom?”), so Greek uses the accusative case.

Masculine singular article and noun:

ο καθηγητής (nominative, subject) – “the professor”
τον καθηγητή (accusative, direct object) – “(ask) the professor”

So:

Ο καθηγητής ρωτάει τον φοιτητή.
“The professor asks the student.”
Ο φοιτητής ρωτάει τον καθηγητή.
“The student asks the professor.”

Notice how ο → τον and καθηγητής → καθηγητή in the object position.

What does αν mean here? Is it “if” or “whether”? How is it different from εάν?

In this sentence αν introduces an indirect question:

…ρωτάνε τον καθηγητή αν αυτή η λύση είναι η πιο απλή.
“They ask the professor if / whether this solution is the simplest.”

Functions of αν:

Conditional “if”
- Αν βρέχει, δεν θα πάμε. – “If it rains, we won’t go.”
“If / whether” in indirect questions
- Ρωτάω αν είναι σωστό. – “I ask if/whether it is correct.”

εάν is basically a more formal / older version of αν. In modern Greek:

In speech, αν is far more common.
In writing, you might see εάν in more formal texts, but the meaning is the same.

You could write:

…ρωτάνε τον καθηγητή εάν αυτή η λύση είναι η πιο απλή.
This is grammatically fine, just a bit more formal.

Why do we say αυτή η λύση? Why both αυτή and η before λύση?

αυτή is a demonstrative adjective/pronoun (“this”), and η is the definite article (“the”).

λύση = solution (fem., singular)
η λύση = the solution
αυτή η λύση = this solution

The usual pattern in Greek is:

(demonstrative) + article + noun
αυτή η λύση = “this solution”
εκείνος ο άνθρωπος = “that man”

You cannot normally drop the article here; αυτή λύση sounds wrong in standard modern Greek.

You can also place the demonstrative after the noun with the article repeated:

η λύση αυτή = this solution (more emphatic or a bit more formal)

Both αυτή η λύση and η λύση αυτή are correct; αυτή η λύση is more neutral and common.

Why are αυτή, η, λύση, and η πιο απλή all feminine singular? How does agreement work?

Greek makes all the related words in a noun phrase agree in gender, number, and case.

Here:

λύση – noun, feminine, singular, nominative
αυτή – demonstrative, feminine, singular, nominative
η – article, feminine, singular, nominative
η πιο απλή – “the simplest” (article + adjective), feminine, singular, nominative

The structure is:

αυτή η λύση – this solution
(αυτή η λύση) είναι η πιο απλή – (this solution) is the simplest

So everything referring to λύση is feminine singular nominative:

αυτή (this) – matches λύση
η (the) – matches λύση
πιο απλή (simpler / simplest) – matches λύση

This agreement is obligatory in Greek.

How does η πιο απλή mean “the simplest”? Isn’t πιο just “more”?

Yes, πιο literally means “more”, and απλή means “simple”.

πιο απλή = “more simple” / “simpler”

But in Greek, when you add the definite article to a πιο + adjective phrase, it usually becomes a superlative:

η πιο απλή (λύση) = “the most simple (solution)” → “the simplest solution”
ο πιο γρήγορος (δρόμος) = “the fastest way”
το πιο δύσκολο (μάθημα) = “the most difficult / hardest subject”

So:

πιο απλή = (a) simpler
η πιο απλή = the simplest

There is also an older / more formal synthetic superlative:

η απλούστερη (λύση) = “the simplest solution”

Both η πιο απλή and η απλούστερη are correct. In everyday modern Greek, η πιο απλή is more common.

Could we change the word order to αν η λύση αυτή είναι η πιο απλή? Is that still correct?

Yes, that is correct and natural:

…αν αυτή η λύση είναι η πιο απλή.
…αν η λύση αυτή είναι η πιο απλή.

Both mean “if/whether this solution is the simplest.”

Differences:

αυτή η λύση – more neutral, very common
η λύση αυτή – slightly more emphatic, can sound a bit more formal or contrastive (“this solution (as opposed to others)”)

Greek word order inside a noun phrase is flexible, as long as the demonstrative, article, and noun remain in one of the standard patterns:

αυτή η λύση
η λύση αυτή

The rest of the clause είναι η πιο απλή stays the same.

Could the order be …ρωτάνε αν αυτή η λύση είναι η πιο απλή τον καθηγητή?

That order is possible but feels unnatural in standard modern Greek.

Normal, natural order:

…ρωτάνε τον καθηγητή αν αυτή η λύση είναι η πιο απλή.

Here, the direct object τον καθηγητή comes directly after the verb ρωτάνε, and the αν-clause follows.

If you move τον καθηγητή to the very end:

…ρωτάνε αν αυτή η λύση είναι η πιο απλή τον καθηγητή.

this sounds marked or awkward, unless you have some special emphasis or poetic style. In everyday speech and writing, keep τον καθηγητή right after ρωτάνε.

What is the nuance of λύση compared to απάντηση?

Both can translate as “answer” in English, but they’re used differently:

λύση = solution (to a problem, exercise, equation, situation)
- η λύση του προβλήματος – the solution to the problem
- η λύση της άσκησης – the solution to the exercise
απάντηση = answer (to a question, reply)
- η απάντηση στην ερώτηση – the answer to the question
- δίνω απάντηση – I give an answer / I reply

In your sentence, they are asking the professor whether this solution is the simplest one, so λύση (solution) is the right word, not απάντηση.