Complete square formula: the square of the sum (or difference) of two numbers is equal to the sum of their squares, plus (or minus) twice their product.
It is called the complete square formula. In order to distinguish, we call the former the complete square formula of the sum of two numbers and the latter the complete square formula of the difference between two numbers.
(a+b)2=a2+2ab+b2，(a-b)2=a2-2ab+b2 .
A and b in the formula can be monomials or polynomials.
If you can't directly apply the formula, you must be good at transforming and using the formula.
Sample solution:
Example: Use the complete square formula to calculate:
(-4x+3y)2 .
(-a-b)2 .
Analysis: This example changes the signs of A and B in the formula. Taking the second subtitle as an example, the simplest way to deal with this problem is to regard (-a) in this formula as A in the original formula and (1 B) as B in the original formula, and then directly apply the formula to calculate.
Answer: 16x2-24xy+9y2. a2+2ab+b2 .