1. When proving that a series is an arithmetic (proportional) series, the arithmetic (proportional) series with tolerance (common ratio) should be written in the final conclusion.

2. When proving the inequality in the last question, if one end is a constant and the other end is a formula containing n, the scaling method is generally considered. If both ends are formulas with n, mathematical induction should be considered, and how to transform the current formula into the target formula should be scaled appropriately.

3. When proving inequality, sometimes the constructor is very simple, so you should have the consciousness of constructor.

Second, the problem of solid geometry

1, it is easier to prove the relationship between line and surface, and generally it is not necessary to establish a system.

2. It is best to establish a system when solving the problems such as the angle formed by straight lines on different planes, the included angle between lines and planes, the dihedral angle, the existence problem, the height, surface area and volume of geometry.

3. Pay attention to the relationship between the cosine value (range) of the angle formed by the vector and the cosine value (range) of the angle (symbol problem, obtuse angle problem, acute angle problem).

Third, the probability problem.

1, find out all the basic events included in the random test and the number of basic events included in the request event.

2. Find out what probability model it is and which formula to apply.

3. Remember the formulas of mean, variance and standard deviation.

4. Pay attention to basic methods such as enumeration and tree diagram when counting.

5, pay attention to put back the sample, don't put back the sample.

6. Pay attention to the penetration of scattered knowledge points (stem leaf diagram, frequency distribution histogram, stratified sampling, etc. ) in the big question.

Fourthly, the conic problem.

1, pay attention to solving the trajectory equation, and consider three kinds of curves (ellipse, hyperbola and parabola). Ellipse is the most frequently tested, and the methods include direct method, definition method, intersection method, parameter method and undetermined coefficient method.

2, pay attention to the straight line, know the midpoint of the chord, commonly used point difference method, pay attention to the range of independent variables.