Object pronouns

no tienes que preocuparte.

You don't have to worry

Why do we need the TE pronoun?

Also, why not say no tienes que preocuparse?

¡Hola Ken3883!

In this case, te is a reflexive pronoun and we need to include here because the verb preocuparse “to worry” (in the sense of “I am worried” or “I worry about you”) is a reflexive (or “pronominal”) verb. This kind of verb shows that the person performing the action and the person receiving the action are the same (so literally, the sentence No tienes que preocuparte means “You don't have to worry yourself”). You can find a full explanation on these kinds of verbs in Lesson 7.5: “Actions You Do to Yourself: Reflexives.”

As for why we don't say “No tienes que preocuparse”, that's because the reflexive pronoun always has to match the subject of the verb - even when the reflexive verb is in the infinitive. (It makes sense if you look at this literally: “No tienes que preocuparse” would mean “You don't have to worry oneself,” which doesn't match up.)

If you still have any questions about this after going through the lesson, don't hesitate to ask! 

Saludos,

Liss