Factorization is one of the most important identical deformations in middle school mathematics. It is widely used in elementary mathematics and is a powerful tool for us to solve many mathematical problems. The factorization method is flexible and skillful. Learning these methods and skills is not only necessary to master the content of factorization, but also necessary to cultivate students' problem-solving skills.

Developing students' thinking ability plays a very unique role. In junior high school mathematics textbooks, the methods of extracting common factors, using formulas, grouping decomposition and cross multiplication are mainly introduced. There are also several methods in the competition, such as adding items separately, undetermined coefficient method, double cross method, rotational symmetry method and so on.

Common factor: The common factor of each term is called this polynomial term. Extraction method of common factor: Generally speaking, if every term of a polynomial has a common factor, you can put this common factor outside brackets and write the polynomial in the form of factor product. This method of decomposing factors is called extracting common factors.

AM+BM+CM = M (A+B+C) Specific methods: When all the coefficients are integers, the coefficients of the common factor formula should take the greatest common divisor of all the coefficients; The letter takes the same letter for each item, and the index of each letter takes the smallest number. If the first term of a polynomial is negative, a "-"sign is usually put forward to make the coefficient of the first term in brackets positive.