GRAMMAR DETAIL

ばいい

need only; should

Presents an appropriate action in the conditional form as a way to achieve a goal or solve a problem.

Examples

道が分からなければ、駅員に聞けばいい。

If you do not know the way, you can just ask a station employee.

疲れているなら、今日は早く休めばいい。

If you are tired, you should rest early today.

申込みはこの用紙に名前を書けばいいです。

To apply, you only need to write your name on this form.

Structure: Add いい to a verb's ば conditional form to suggest a solution or suitable action.
Basic usage: 申込みはこの用紙に名前を書けばいいです。 gives a simple instruction for applying.

A method and an obligation
- 聞けばいい presents asking as a solution. It differs from 聞かなければならない, which emphasizes an obligation.
Using it in a question
- どうすればいいですか asks what course of action to take. Rather than treating いい as merely an evaluation, convey the sentence's function as advice or a question about a method.