把一个多项式分解因式 ,关键是因式分解方法的选择 .首先 ,考虑有没有公因式可提取 .在提取公因式后 ,或没有公因式可提取时 ,可根据多项式的项数及特点选择因式分解的方法 .　　一、二项式对于二项式 ,通常先考虑是否可用平方差公式进行因式分解 .若不能 ,则可考虑用添项法来 The factor of factoring a polynomial is the choice of the factorization method. First, consider whether there is a common factor to extract. After the common factor is extracted, or there is no public factor to extract, the number of items according to the polynomial and Select the factorization method. One or Binomial For the binomial formula, first consider whether the factorization formula can be used for factorization. If not, consider using the addition method.