(a) using the formula method:

We know that algebraic multiplication and factorization are inverse deformations of each other. If the multiplication formula is reversed, the polynomial is decomposed into factors. So there are:

a2-b2=(a+b)(a-b).

a2+2ab+b2=(a+b)2 .

a2-2ab+b2=(a-b)2 .

If the multiplication formula is reversed, it can be used to factorize some polynomials. This factorization method is called formula method.

(2) Variance formula.

Variance formula:

Equation (1): a2-b2=(a+b)(a-b).

(2) Language: the square difference of two numbers is equal to the product of the sum of these two numbers and the difference of these two numbers. This formula is the square difference formula.

(3) Factorization.

1, factorization, if there is a common factor, first extract the common factor, and then further decompose.

2. Factorization must be carried out until each polynomial factor can no longer be decomposed.

note:

① The number of items is three; Two terms are the sum of squares of two numbers, and the signs of these two terms are the same; A term is twice the product of these two numbers.

(2) If there is a common factor in polynomial, the common factor should be put forward first, and then decomposed by formula.

③ A and B in the complete square formula can represent monomials or polynomials. Here as long as the polynomial as a whole.

(4) Factorization must be decomposed until every polynomial factorization can no longer be decomposed.