初中数学教材中关于分解因式有四种基本方法:提公因式法、公式法、分组分解法及式子ｘ2+(ａ+ｂ)ｘ+ａｂ=(ｘ+ａ)(ｘ+ｂ)法.但是,有些多项式是无法直接使用这些方法进行分解的,必须经过适当的变形后才能分解因式.为使读者正确、熟练地掌握分解因式,现介绍几种基本变形.一.符号变 There are four basic methods for the factor of factorization in the junior middle school mathematics textbooks: public factor method, formula method, group decomposition method and the formula x2+(a+b)x+ab=(x+a)(x+b) method However, some polynomials cannot be directly decomposed using these methods, and they must be decomposed after appropriate deformation. To enable the reader to grasp the factorization factors correctly and skillfully, several basic deformations are introduced.