二次函数是初中数学教学内容的重点之一,也是初中数学与高中教学联系的纽带.而函数类应用型问题中,又以二次函数问题见多,它是函数部分的难点,它也是各地中考命题的热点.一般情况下,二次函数的最值由顶点坐标来确定,这是大多数同学容易掌握的.但有时函数的最值不是由顶点坐标来确定,这一点很容易被同学们疏忽.笔者将从以下几个方面来阐 The quadratic function is one of the focuses of the junior high school mathematics teaching content, and it is also the link between the junior middle school mathematics and the high school teaching. However, in the function-type application problem, the quadratic function problem is more common. It is a difficult part of the function, and it is also a part of the The hot spot of the exam topic. Under normal circumstances, the maximum value of the quadratic function is determined by the vertex coordinates. This is easy for most students to grasp. But sometimes the function’s maximum value is not determined by the vertex coordinates. This is easily understood by the students. Oversight. The author will explain from the following aspects