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有关根据函数图象确定自变量x的取值范围的问题,能考查学生的看图能力、数形结合思想,以及将图形语言转化为数学语言的能力.解题时若能特别关注图象的交点,对其几何性质和数量关系的意义进行分析,则能准确快速地解决问题.一般解题步骤是:1找界点;2画分界线(垂直于x轴的直线);3分类;4确定范围.本文试以各地中考试题为例,说明如下.一、两个函数图象相交1、一次函数与一次函数例1(2014毕节)如图1,函数y=2x和
Regarding the problem of determining the range of the argument x from the function image, one can examine students’ ability to see pictures, the combination of ideas with numbers, and the ability to translate graphics languages into math languages. The intersection points, the analysis of the relationship between the geometric properties and the number of meaning, you can accurately and quickly solve the problem. The general problem-solving steps are: 1 to find the cut-off point; 2 boundary (perpendicular to the x-axis); 3 classification; 4 Determine the range.This article takes the middle school exam questions as an example, described as follows.One, the two function images intersect 1, a function and a function Example 1 (2014Byte) As shown in Figure 1, the function y = 2x and