There are roughly the following kinds of evaluation domains in senior one. Each of them should pay attention to the problem of definition domain (that is, the possibility that some value domains may be omitted when paying attention to x∈R). In addition, the function image evaluation field is basically used below (in fact, it is possible to understand its principle without images, but many principle teachers may not speak it in Grade One. Then be sure to find the law of its function image and summarize it yourself)
1, monotone interval evaluation domain. For monotonically increasing or decreasing regions, the maximum and minimum values are located at the two ends of the function image respectively. This is easy to ask. First, it is proved that the function is monotonous in a certain section, and then the values of the two endpoints are found.
2. Separation constant. This method is used in the case of y= binary algebraic division. It is to regard the algebraic expression of a molecule as a multiple of the algebraic expression of the denominator plus a constant. For example: (2x+3)/(x+ 1), the molecule can be regarded as 2(x+ 1)+ 1, so that the original formula can be changed into a constant plus a translation inverse proportional function. Specific Baidu separation constant method.
3. Quadratic function value domain. Draw directly and omit.
4. Check the function and omit it.
5, discriminant method, direct Baidu library
6. The range of composite function. Firstly, the range of the inner function is found as the definition range of the outer function, and then it is solved by the method of general evaluation range. Leave it alone.
That's probably all I remember. I just said it casually on it.