First, put the coefficient in front of the quadratic term, and then, regardless of the constant term, add half the square of the quadratic term coefficient in brackets to make it completely flat. After subtracting the number you added, write the first three terms in square form, and then calculate the constant.

Complete square formula:

(1) The square of the sum of two numbers is equal to the sum of their squares plus twice their product.

(2) The square of the difference between two numbers is equal to the sum of their squares minus twice their product.

(a-b)_=a_+b_-2ab

Memorize the formula: the first square, the last square, twice in the middle, and the symbol looks forward.

Structural characteristics of these two formulas:

1) On the left is the multiplication of two identical binomials, and on the right is the trinomial, which is the sum of the 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 symbols on the right are connected with "+"; When the two symbols on the left are opposite, the square items on the right are connected by "+"and then multiplied by "-"(note: the symbol of this item is 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.