There's a pretty good description in the Academy Grammar that I'd only have to condense, but I still don't feel up to it. I've already posted this link in several places but I'm posting it here too: this is our best post about the subject at the moment: https://www.duolingo.com/comment/7075383
Are you asking if to create the infinitive we just need to remove the r from the the present tense? In that case, in many cases yes. But it's not always the case and it might not be the best way to think about it. In many methods, they actually use the infinitive to know how to use the present tense form of a given verb (they use it as the base form of the verb)(btw, if you look for verbs in the dictionary, you will find them under their infinitive form). In Swedish verbs fall into different groups, which follow specific structures. For instance verbs of the group 1 (the most common) like "titta", "prata", "tala" become "tittar" "pratar", "talar" in their present form. In this case the only difference between infinitive and present tense is the r, like you're saying. But it is not the case for group 2 verbs, like "läsa" -> present: "läser" and group 3 and 4.
I personally don't use the groups as references (it's good to know that they exist for patterns). I tend to learn the infinitive, and the present, preterite and supinum, which allows me to use them in sentences.
I hope it's useful :)
I have been searching but can't seem to figure this out. When do we use rita compared to ritar? Barnen alskar ritar = the children love drawing, Jag ritar en hund = I draw a dog So ritar is a present verb and then att rita is a past tense infinitive? Have I got this right or not?
The way I think of it is this: the infinitive is used when you need to do a verb, not when you are doing a verb. For example, I like to speak vs I speak/I am speaking. In Swedish, Jag gillar att prata vs Jag pratar.
So in the current example: The children love (to do) drawing = Barnen älskar att rita. Barnen älskar ritar is incorrect as "älskar" seems to be acting as a modal verb which Duolingo says requires using the infinitive. The correct sentence, using ritar would be: Barnen ritar = The children are drawing,
Att rita is not past tense infinitive, it's just the infinitive.
I hope this helps!
As a complement: Ritar and rita are two different forms of the same verb, and they are used in different locations in the sentence, and clauses.
Att rita=infinitive/base form of verb Ritar= present tense Att ha ritat= perfect infinitive.
Each clause accepts only one conjugated verb (like "ritar"), but the you have other verbs under other forms like the infinitive. Some verbs accept an infinitive behind them without att (modal vetba, but not only), others with att.
E.g.: Barnen ritar Barnen älskar att rita [needs att] Barnen vill rita [modal, no att] Barnen börjar/försöker rita [non modal verbs but don't need att]
The tip of lovele4nin- thinking gör/göra is very useful to learn patterns and starting to feel the language :)