Past participles and adjectives can metamorphose into masculine/feminine and singular/plural forms in order to reflect the gender and number of nouns. This metamorphism is called agreeing.
The past participle agrees selectively- agreeing only with certain nouns in particular situations.
The adjective on the other hand is hopelessly indiscriminate when it comes to agreement- agreeing with whichever noun it is coupled with.
The adjective guide describes the richly varied masculine/feminine and singular/plural forms that adjectives can take.
La musique - la seule langue universelle
Les petits ruisseaux font les grandes rivières.
Grand bonheur, grand péril. -- Proverbe
When an adjective modifies a masculine and a feminine noun at the same time, a masculine plural adjective is used.
|Déplacez la chaise et le banc verts dans ce coin.|
|Move the green chair and bench to that corner.|