The multiplication formula and factorization of PEP are in the last chapter of the first volume of Grade 8. The multiplication formulas are: 1, and the complete square formula: the square of the sum or difference of two numbers is equal to twice the sum of the squares of two numbers and the product of two numbers; 2. Square difference formula: the product of the sum and difference of two numbers is equal to the square difference of two numbers; These two formulas are obtained by polynomial multiplication. Factorization is to write polynomials in the form of order products, which is the inverse of multiplication formula and is mainly used to simplify the calculation process.