The sum of the squares of 1 is equal to the sum of their squares plus twice their product. Formula writing: (a+b)? =a？ +2ab+b？
The square of the difference between two numbers is equal to the sum of their squares minus twice their product. Formula writing: (a-b)? =a？ -2ab+b2
Structural characteristics of two formulas
1, the left is the product of two identical binomials, and the right is the trinomial, which is the sum of squares of two items in the binomial on the left, plus or minus twice the product of these two items;
2. When the two symbols on the left are the same, all the symbols on the right are connected with "+"; When the symbols of the two items on the left are opposite, the square items on the right are connected by "+"and then multiplied by "-"twice (note: the symbols of the items are not included here).
3. The letters in the formula can represent specific numbers (positive or negative numbers) or mathematical formulas, such as monomials or polynomials.
Formula method of polynomial multiplication;
Complete square sum formula (a+b) 2 = a 2+2ab+b 2. Complete square difference formula (a-b) 2 = a 2-2ab+b 2.
Law of monomial multiplication:
The multiplication of monomials is to multiply their coefficients with the same letters respectively. For letters contained only in monomials, they are used as factors of the product together with their exponents.
The Law of Polynomial Multiplying Monomial:
Multiplying polynomial with monomial means multiplying each term of polynomial by monomial according to the distribution law, and then adding the products.
Polynomial Multiplication Polynomial Rules:
Multiply each term of the first polynomial by the next polynomial, then convert the polynomial multiplication polynomial into a monomial multiplication polynomial, and then operate according to the law of monomial multiplication polynomial.
The first two terms and the last two terms are squared, twice the product of the first two terms and the last two terms are placed in the middle, and the symbol follows the center. (that is, calculate the power of two terms, then calculate the product of two terms, multiply by 2, and then put this number in the middle of the power of two numbers. The symbol between the preceding numbers follows the symbol in the middle of the original formula, with+for the complete sum of squares formula,-for the complete difference of squares formula, and+for the following symbols).