Formal:
* J'aimerais un sac de carottes. (This is the most common and polite way to say it.)
* Je voudrais un sac de carottes. (This is also polite, but slightly less formal than "J'aimerais.")
Informal:
* Je veux un sac de carottes. (This is less formal and can be used with friends or family.)
* Donnez-moi un sac de carottes. (This is very informal and can be used with someone you know well.)
Note:
* "Un sac de carottes" translates to "a bag of carrots."
* You can replace "un sac" with "un paquet" (a packet) or "une poche" (a pouch) depending on the type of bag.
For example, if you are at a market and see carrots in a loose pile, you might say "J'aimerais un sac de carottes, s'il vous plaît" (I would like a bag of carrots, please).