2. The nature of inequality: It should be noted that when both sides of inequality are multiplied or divided by a negative number at the same time, the direction of inequality will change.
3. Symbols of trigonometric functions: We need to pay attention to the symbols and periodicity of sine, cosine, tangent and other functions in each quadrant.
4. Logarithmic operation: You need to pay attention to the range of logarithm base and real number, and the use of base-changing formula.
5. The concepts of derivative and integral: Understand that derivative represents the tangent slope of the function at a certain point, and integral represents the area under the curve.
6. Convergence of series: Pay attention to the convergence speed and conditions of series to avoid divergence.
7. Vector product: We need to pay attention to the difference between vector product and dot product and the application of cross product.
8. permutation and combination: pay attention to the calculation formula and application of permutation and combination to avoid repeated calculation.
9. Probability theory: we need to pay attention to the concepts of probability, conditional probability and independent events, as well as the application of total probability formula and Bayesian formula.
10. Analytic geometry: In analytic geometry, we need to pay attention to the properties and relationships of lines, circles, ellipses, hyperbolas, and the application of coordinate method.