Learn French: Il fait attention aux racines, aux mèches et aux pointes. - He pays attention to the roots, to the locks, and to the tips.

In French, the prepositions à, de, and en must be repeated before every single noun in a list. Because the expression is faire attention à (to pay attention to), that à has to appear before roots, locks, and tips, regardless of how we group them in English.

Does the repetition rule for à still apply even though it's hidden inside the contraction aux?

Yes! Because aux is a mandatory contraction of à + les, it still contains the preposition à. Whenever a repeated preposition contracts with a definite article (le or les), you must repeat the fully contracted form (au, aux, du, or des) before each applicable item in your list.

What context are we in here with words like racines, mèches, and pointes?

This sentence is talking about a hair salon! In hairdressing, les racines are the hair roots, les pointes are the ends or tips, and les mèches refers to locks of hair, streaks, or highlights.

Why is there no article before attention? Shouldn't it be Il fait de l'attention?