[StijnA]

Hello came across very odd question in some books:

1 : 花は赤いです。(The flower is red.)

2 : 旗は赤く、白く、青い です。(The flag is red, white and blue.)


Shouldn't it be? Now it made me doubt again.

1 : 花は赤です。

2 : 旗は赤、白、青 です。

Shouldn't い only be used with adjectives, not with a noun?
What is the use of -ku in a color 赤 -> 赤く ?

Thank you!