Why are there two different forms of the adjective "useful"?
- 役に立つ
- 役に立ち
When I looked up on Jisho.org (here), the page would show an entry for the former even if I typed the latter in the search box.
Below are a few examples that I found (from DuoLingo.com's drills):
- この本はとても役に立ちます。
- この本は日本の歴史を学ぶのに役に立つ。
- 役に立つ文章はどこですか。
- 彼は役に立ちません。