1试题呈现若函数y=|x-3|+|x+1|+|x-a|的图像关于垂直x轴的直线对称,则实数a=____。2思路分析本题源于某高中版数学杂志,其所呈现的基本解法主要运用初中知识,且难度尚可。于是,在一节函数专题习题课上,笔者大胆地让九年级学生也尝试求解,遗憾的是经过3分钟的思考后,仍然没有学生给出基本的解题思路;随后笔者又让学生自由组合,分 The 1 test question shows that if the image of the function y=|x−3|+|x+1|+|x−a| is symmetrical about the vertical x-axis, the real number a=____. 2 Thinking analysis This question originates from a high school edition of mathematics magazine. The basic solution it presents mainly uses junior high school knowledge, and the difficulty is acceptable. So, in a function topic training class, the author boldly allowed the ninth-grade students to also try to solve, but unfortunately after three minutes of thinking, there is still no student to give the basic problem-solving ideas; then the author allowed the students to freely combine ,Minute