plz 4:00前答覆
1.(a+b)(a-b)+(b+c)(b-c)+(c-a)(c-a)
2.(x+y)(x-y)
收錄日期: 2021-04-15 20:15:36
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090318000051KK00682