Yes, it is a compound adjective and should be hyphenated. In that context, 'hard' is an adverb modifying 'working'. If you do not hyphenate it, you are using two separate adjectives, 'hard' and 'working'.
No, "hardworking" is not hyphenated.
more hardworking, most hardworking
It is not hyphenated.
Hardworking as a dog or beaver cuz animals word hard or hardworking as a builder cuz they work hard to build houses and buildings?
Hardworking is the correct spelling.
Motorcycle is not hyphenated
No it's not hyphenated.
words are only hyphenated when they have a separate meaning when separated than they do when hyphenated
John is very hardworking
Yes it should be hyphenated.
It can be. Some words can be seen both hyphenated and non-hyphenated.
No. Well above is not hyphenated.