Learn Finnish: Hän yritti läpäistä kurssin valmistautumatta. - He tried to pass the course without preparing.

It is formed from the verb valmistautua (to prepare oneself). The ending -matta is the third infinitive abessive, which translates to "without doing". You build it by taking the strong stem of the verb (valmistautu-) and adding -ma- followed by the "without" ending -tta.

Why does kurssin end in -n instead of being kurssi or kurssia?

Kurssin is the object of the verb läpäistä (to pass). Because the sentence has a clear subject (hän) and passing a course is viewed as a complete action, the total object takes the accusative -n ending. If the action were incomplete or ongoing, you would use the partitive form kurssia.

What type of verb is läpäistä (to pass)?

It is a verb type 4, specifically ending in -stä. Type 4 verbs can be a bit tricky because their stem changes to add -se- before personal endings. For example, "I pass" is läpäisen and "he passes" is läpäisee. Here, it stays in its basic infinitive form because it follows yritti (tried).

Could I just use the word ilman (without) to say "without preparing"?