Vieux - singular or/and plural?

Question

Hi,I thought that "vieux" can be singular AND  plural but the quiz says it is only singular.

Accepted Answer

Hi Larry, 
The adjective 'vieux' can be singular or plural as in -
un vieux manteau = an old coat 
un vieux copain = an old friend
but in front  an -h mute or a vowel, it will become 'vieil' -  
un vieil homme 
un vieil hotel 
un vieil ami 
In the plural -
C'était de vieux amis = They were old friends
C'était de vieux hotels = They were old hotels
etc.

Answer

In the lesson it says that vieux doesn't change in the masculine plural -- and it doesn't (as opposed to beu, for example):Le vieux homme -- The old man.Les vieux hommes -- The old men.But there is a different form of vieux for the masculine singular, if the noun starts with a vowel or h muet:Un vieil amour. -- An old love.