Learn Swedish: Kan du bevisa motivet är falskt? - Can you prove the motive is false?

Just like in English, you can often drop the subordinating conjunction att (that) in Swedish. This happens most often when the clause acts as the object of a verb like bevisa (to prove), tro (to believe), or säga (to say).

Is it more common to include or leave out att in a sentence like this?

Leaving out att is very common in everyday spoken Swedish and casual writing. However, in formal texts, it is usually better to keep att to make the sentence structure perfectly clear: Kan du bevisa att motivet är falskt?

If I want to say "prove the motive is not false", where does inte go?

The phrase motivet är falskt is a subordinate clause (a mini-sentence inside the main one). In Swedish subordinate clauses, sentence adverbs like inte must come before the verb. So you would say: Kan du bevisa (att) motivet inte är falskt? Even though att is hidden here, the subordinate clause word order rule still applies!

Why does the adjective falskt end in a -t here?