数学教学的目的是培养学生分析问题和解决问题的能力.经常会遇到含字母系数的二次函数在闭区间上的最值问题.对这类问题学生始终感到很难,其实也很有规律可循.请看下面的例子. The purpose of mathematics teaching is to cultivate students’ ability to analyze problems and solve problems. They often encounter the problem of the value of the quadratic function that contains the letter coefficient in the closed range. Students always find it difficult to deal with such problems. In fact, they are also very regular. Follow it. See the example below.