1, square difference formula: a? -B? =(a+b)(a-b).

2. Complete square formula: a? +2ab+b？ =(a+b)？ .

3. Cubic sum formula: A? +b？ =(a+b)(a？ -ab+b？ )。

4. Cubic difference formula: a? -B? =(a-b)(a？ +ab+b？ )。

5. Complete cubic sum formula: a? +3a？ b+3ab？ +b？ =(a+b)？ .

6. Complete cubic difference formula: a? -3a？ b+3ab？ -B? =(a-b)？ .

7. Three complete square formulas: A? +b？ +c？ +2ab+2bc+2ac=(a+b+c)？ .

8. the formula of cubic sum of three terms: a? +b？ +c？ -3abc=(a+b+)(a？ +b？ +c？ -ab-bc-ac).

9. Area of rectangle = length × width.

10, square area = side length × side length.

1 1, triangle area = base × height ÷2.

12, area of parallelogram = base × height.

13, trapezoidal area = (upper bottom+lower bottom) × height ÷2.

14, area of circle = π× radius× radius.

15, the solution of quadratic equation in one variable:-b+√ (B2-4ac)/2a-b-b+√ (B2-4ac)/2a.

Junior high school mathematics learning methods:

1, get ready:

In the unit preview, we can read roughly, understand the learning content in the recent stage, read carefully in the classroom preview, pay attention to the formation process of knowledge, and record the concepts, formulas and laws that are difficult to understand, so that we can listen to the class with questions.

2. Listen carefully:

Listening to lectures should include listening, thinking and remembering. Listen, listen to the ins and outs of the formation of knowledge, listen to the key and difficult points, and listen to the answers and requirements of examples. Thinking, one is to be good at association, analogy and induction, and the other is to dare to question and ask questions. Taking notes means taking notes in class-methods, doubts, requirements and precautions.

3. Seriously solve the problem:

Classroom exercises are the most timely and direct feedback, and must not be missed. Don't rush to finish your homework, look at your notebook first, review your learning content, deepen your understanding and strengthen your memory.

4, timely error correction:

Classroom exercises, homework, tests and feedback should be consulted in time, the causes of wrong questions should be analyzed, and relevant calculation training should be strengthened when necessary. Ask your classmates and teachers if you don't understand. Don't let the problem hang in the air. Get into the good habit of doing things today.