Series Content INTRO 完美數 | Perfect Numbers LESSON 1 恆等式簡介 | Introduction to Identity LESSON 2 幾個重要的恆等式 | Some Important Identities LESSON 3 因式分解 | Factorization LESSON 4 因式分解 (恆等式) | Factorization by Identities LESSON 5 因式分解 (十字相乘法) | Factorization by Cross-method ADD-ON 帕斯卡三角形 | Pascal’s Triangle