Dobbelttaket er i og for seg raskt, men vanskelig.

I og for seg is an idiomatic expression. It often means something like:

• in itself
• in a way
• strictly speaking
• when considered on its own

It slightly softens or qualifies what follows. In this sentence, it suggests that if you look at the thing by itself, it is raskt, but there is still a contrasting problem: it is vanskelig.

A related expression is i seg selv, but i og for seg often sounds a bit more conversational and nuanced.

Because Norwegian usually writes compound nouns as one word, unlike English, which often separates them.

So dobbelttaket is a compound noun in definite form. Very roughly, it can be seen as:

• dobbelt-
  • tak
• then the definite ending -et

This is very normal in Norwegian. English learners often want to split compounds up, but Norwegian strongly prefers one written word for this kind of noun.

The ending -et is the definite article attached to the noun. Norwegian usually adds definiteness to the end of the noun instead of using a separate word like the.

So:

• et dobbelttak = an/the double take in indefinite form
• dobbelttaket = the double take

The ending -et shows that the noun is neuter singular definite.

Because the adjective agrees with the noun.

Here, dobbelttaket is a neuter singular noun, so the adjective in predicate position takes the neuter form:

• rask = common gender singular
• raskt = neuter singular
• raske = plural / definite

Since the sentence is saying Dobbelttaket er ... raskt, the adjective must match the neuter noun, so raskt is correct.

This is a very common learner question.

Many Norwegian adjectives add -t in the neuter, but some do not. Adjectives ending in -ig, -lig, and some others usually do not add an extra -t in the neuter form.

So:

• en vanskelig oppgave
• et vanskelig spørsmål
• vanskelige oppgaver

That is why the sentence has:

• raskt
• but vanskelig

Even though both describe a neuter noun.

The structure is:

• Dobbelttaket = subject
• er = finite verb
• i og for seg = adverbial expression
• raskt, men vanskelig = predicate adjectives

So the pattern is:

Subject + verb + adverbial + adjective phrase

This follows normal Norwegian main-clause word order, where the finite verb comes early in the clause. Since the subject comes first, er comes right after it.

Yes, it has some flexibility.

For example, you can also say:

• I og for seg er dobbelttaket raskt, men vanskelig.

That version gives a little more emphasis to the qualifying phrase.

The position in your sentence is also very natural:

• Dobbelttaket er i og for seg raskt, men vanskelig.

Putting i og for seg at the very end would usually sound less natural here, because it most naturally comments on the whole statement or on raskt.

Because both adjectives are linked to the same verb.

The structure is basically:

• Dobbelttaket er raskt, men vanskelig.

Both raskt and vanskelig are predicate adjectives after er. Norwegian, like English, does not need to repeat the verb here.

Compare English:

• It is fast but difficult.

You would not normally say:

• It is fast but is difficult

unless you wanted special emphasis.

Men means but. It is a coordinating conjunction that links two contrasting descriptions:

• raskt
• vanskelig

So the sentence sets up a contrast: one positive or easier-sounding feature versus one negative or more challenging one.

This use is very similar to English but.