1, square difference formula: a? -B? =(a+b)(a-b).

2. Complete square formula: a? +2ab+b？ =(a+b)？ .

3. Cubic sum formula: A? +b？ =(a+b)(a？ -ab+b？ )。

4. Cubic difference formula: a? -B? =(a-b)(a？ +ab+b？ )。

5. Complete cubic sum formula: a? +3a？ b+3ab？ +b？ =(a+b)？ .

6. Complete cubic difference formula: a? -3a？ b+3ab？ -B? =(a-b)？ .

7. Three complete square formulas: A? +b？ +c？ +2ab+2bc+2ac=(a+b+c)？ .

8. the formula of cubic sum of three terms: a? +b？ +c？ -3abc=(a+b+c)(a？ +b？ +c？ -ab-bc-ac).

Factorization mainly includes:

Cross multiplication, undetermined coefficient method, double cross multiplication, symmetric polynomial, rotational symmetric polynomial method, remainder theorem method, etc. There is no universal method to find the root common factor decomposition. The junior high school mathematics textbooks mainly introduce the method of putting forward common factors, using formulas and grouping decomposition. There are French division, addition and subtraction, method of substitution, long division, short division, division and so on.