"It's a law that changed the lives of people."
Translation:C'est une loi qui a changé la vie des gens.
Would it be incorrect to say, ¨C'est une loi qui a changé LES VIES des gens. ?? I am asking if both la vie and les vies are technically correct French, OR if you should always use the singular form for the first part of ¨the noun of noun¨ construction when you are referring to multiples for multiples.
@CSA_GA, Sitesurf gave a neat summary of this at:
Here it is (please excuse formatting glitches). Pay special attention to the second paragraph; it explains why vie de gens does not work.
I think you are referring to the construction I call "noun of noun" = "nom de nom"
This is when the second noun adds information to the first noun about material, content, quality or purpose.
In English, you have two ways of building such cases:
1) you place the second noun in front of the first one and it becomes an adjective:
a stone bridge = un pont de pierre
a travel agency = une agence de voyages
a kitchen knife = un couteau de cuisine
2) you use, as in French "of + noun":
a bottle of milk = une bouteille de lait
a deck of cards = un paquet de cartes
As you could see from the above, using a noun as an adjective is impossible in French (even if most French adjectives can be used a nouns, by the addition of an article).
As a consequence, there are tons of occasions to use a "noun of noun" in French.
Here is one more example to help make it very clear:
Quel est votre nom de famille? ("nom de famille", surname, family name) Quel est le nom du garçon?
Quels sont les noms de famille des femmes?
Quels sont les noms des femmes?
Hope this helps.