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参数范围题是中学数学习题中常见的一类重要问题。通常在解这类题时总是抓住题中的主变量x、y等进行函数或方程角度的分类讨论而获结果。实际上,如果能变换角度思考问题,则常可使解题过程得到简化。这只需先将所给范围题根据题设改写为含参数k的不等式f(x,k)≤0(或其它相应形式),再将参数k与主变量x进行分离,转化为k≤g(x)(或其它相应形式),这时确定参数k的范围问题就已化归为求函数g(x)的值域或最值
The parameter range question is an important class of common problems in the middle school number problem. Usually when solving such a problem, the main variables x, y, etc. in the problem are always grasped for the classification of the function or equation angle to obtain the result. In fact, if you can change the perspective of the problem, you can often simplify the problem-solving process. This only needs to first rewrite the given range question to the inequality f(x, k) ≤ 0 (or other corresponding form) with the parameter k, and then separate the parameter k from the main variable x and convert it to k ≤ g. (x) (or other corresponding form), in which case the problem of determining the range of the parameter k has been reduced to find the value range or the maximum value of the function g(x).