aka, akai or akaku?
 

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!

You know the て form of verbs, right? It exists for adjectives, too. 赤くて, for example, is the て form of 赤い. The て form is what linguists call a "conjunctive" form.

Now, a more literary conjunctive form is to drop the て completely. This is what you see here.