èrxiàngshìdìnglǐ
ㄦˋ ㄒㄧㄤˋ ㄕˋ ㄉㄧㄥˋ ㄌㄧˇ
Simplified 二项式定理
Taivo → Settings → Partner inbox → Make the link. It stays in this browser.
Keep 二項式定理 and it comes back until you know it.