Today, I have compiled five skills for you to answer multiple-choice questions in high school mathematics. I hope I can help students in need and stop quickly!
1. Exclusion method: The so-called exclusion method is to use the information given in the known conditions and options to exclude three wrong answers from the four options, so as to achieve the purpose of correct selection. This is a common method, especially when the answer is a fixed value or has a clear numerical range, it can be eliminated by substituting special points for verification.
The following questions: y=x is odd function, y=sin|x| is even function, and odd function+even function is odd function or even function. Of the four options given, only option B is an odd or even function, so we can immediately exclude the ACD option.
2. Special value verification method: For general mathematical problems, in the process of solving problems, we can specialize the problems, and use the principle that if the problems are not established under special circumstances, they will not be established under general circumstances, so as to achieve the purpose of eliminating the false and retaining the true. It should be noted that the special value method is often used together with the exclusion method.
Substituting the following questions into the special value of 0 obviously excludes the AD option; Substituting x=- 1 obviously does not conform, so the c option is excluded.
3. Extremism principle: The problem to be studied is extreme, so that the causal relationship is more obvious, thus achieving the purpose of solving the problem. Extreme value principle is often used to find extreme value, range, analytic geometry and solid geometry. Many complicated problems can be solved in an instant by applying the extreme principle.
The following questions, directly test AB? In the extreme case of CD, take the midpoint E of AB, the midpoint F of CD, connect EF, and make EF? AB and EF? CD, the calculated value is the maximum.
4. Forward deduction method: that is, using mathematical theorems, formulas, rules, definitions and the meaning of questions, we can get the results through direct calculus and reasoning.
According to the meaning of the question, the following questions can be substituted into the function and its inverse function in turn.
When the previous problems are difficult to solve, we can gradually deduce the qualified conclusions from the options or draw conclusions from the back. This method is often used when doing permutation and combination or probability problems.
Conclusion The above five methods should be used flexibly, and can be used comprehensively in many cases. Remember not to stick to one method.