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二元函数值域问题是高中数学常考的题型,学生在遇到此类题型时,往往错误率较高.本文先介绍一些解决此类问题的几种基本解法,如消元法、不等式法、向量法、三角换元法、化归法等,再通过变题介绍一些特殊解法,从而让学生能更有效地解决此类问题.下面笔者就从几个例题出发系统阐述这类问题的解决方法,希望对学生有所启发.例1已知a,b>0,且ab=a+b+3.(1)求ab的取值范围;
Binary function range problem is often the high school mathematics test questions, students encounter such questions, the error rate is often higher.This article first introduces some of the basic solutions to such problems, such as elimination of the law, Inequality method, vector method, trigonometry method, the law of return, etc., and then introduce some special solutions through the problem, so that students can more effectively solve such problems. The following author from a few examples of the problem set out to explain these issues Solution, hoping to give some inspiration to students.Example 1 is known a, b> 0, and ab = a + b + 3. (1) Find the range of ab;