Questions & Answers about Min nye lejlighed er større end den gamle.
Because lejlighed is a common-gender noun: en lejlighed. With singular common-gender nouns, the possessive is min.
- min lejlighed
- mit hus
- mine bøger
So min nye lejlighed is correct.
After a possessive like min, Danish normally uses the -e form of the adjective. So ny becomes nye in min nye lejlighed.
Compare:
- en ny lejlighed = an new apartment
- min nye lejlighed = my new apartment
- lejligheden er ny = the apartment is new
So the form changes depending on how the adjective is used.