Hun virker positiv.

Because virker means seems, appears, or comes across as, while er means is.

So:

• Hun er positiv = she is positive
• Hun virker positiv = she seems positive / she appears positive

Using virker makes the statement a little less direct. It tells us this is an impression, not necessarily a confirmed fact.

Virker is the present tense of å virke.

A few useful forms:

• å virke = to seem / to appear / to work, depending on context
• virker = seems / appears / works
• virket = seemed / appeared / worked

In this sentence, å virke means to seem.

No. Å virke can have more than one meaning.

Common meanings include:

• to seem / appear
  
  • Hun virker trøtt. = She seems tired.
• to work / function
  
  • Maskinen virker ikke. = The machine doesn’t work.

So the meaning depends on context. In Hun virker positiv, it clearly means seems.

Because positiv is a predicate adjective here. It describes the subject hun after a linking verb like er, blir, virker, ser ut, etc.

This is normal in Norwegian:

• Hun er glad.
• Han virker sint.
• De blir slitne.

So Hun virker positiv follows a very common pattern:

subject + verb + adjective

Because adjectives in Norwegian change form depending on what they describe.

Here, positiv describes hun, which is a singular common-form subject, so the basic form is used:

• Hun virker positiv.
• Han virker positiv.

Other forms:

• Det virker positivt.
  Here det is neuter, so the adjective becomes positivt.
• De virker positive.
  Here the subject is plural, so the adjective becomes positive.

So the adjective agrees with the subject.

Yes, often it can.

Depending on context, positiv can mean:

• positive in attitude
• optimistic
• favorable
• supportive

For example:

• Hun virker positiv. = She seems positive / optimistic.
• Hun er positiv til forslaget. = She is positive about the proposal.

So the exact nuance depends on what is being talked about.

You usually put ikke after the verb:

• Hun virker ikke positiv.

This means:

• She doesn’t seem positive.

This is the normal placement of ikke in a simple main clause like this.

Yes, but it is slightly different.

• Hun virker positiv = She seems positive / comes across as positive
• Hun ser positiv ut = She looks positive

Virker is more general and can be based on overall impression, behavior, tone, attitude, and so on.
Ser ... ut focuses more on appearance, though in real speech the difference can sometimes be small.

No. Norwegian does not use an article here.

After verbs like er, blir, and virker, adjectives usually stand on their own:

• Hun er snill.
• Han virker trett.
• De er glade.

So Hun virker positiv is complete as it is.

A rough guide for an English speaker:

• Hun: the u is not like English oo. It is a more fronted vowel, somewhat similar to the vowel in French tu or German ü.
• virker: the r is pronounced in Norwegian style, which varies by region. The i is like a long ee-type sound.
• positiv: roughly po-si-TEEV, with stress near the end.

A very rough approximation might be:

• hün VEER-ker po-si-TEEV

But exact pronunciation depends on dialect, and English spelling cannot show it perfectly.

In standard modern Norwegian, hun means she.

You may also see:

• ho in some dialects and in Nynorsk
• hen in some contexts as a gender-neutral pronoun, though it is less traditional and depends on usage and style

But in this sentence, hun simply means she.

The past tense is virket:

• Hun virket positiv. = She seemed positive.

Other useful tense examples:

• Hun virker positiv. = She seems positive.
• Hun har virket positiv. = She has seemed positive.
• Hun vil virke positiv. = She will seem positive.

Yes. It is natural and common Norwegian.

You can use this structure for many similar descriptions:

• Hun virker hyggelig. = She seems nice.
• Han virker nervøs. = He seems nervous.
• Læreren virker streng. = The teacher seems strict.

So Hun virker positiv is a very normal kind of sentence pattern to learn.