函数是初中数学的重点,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的函数最值问题又是函数部分的难点。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。下面笔者列举几例加以说明。 Function is the focus of junior high school mathematics, and it is also the link between junior high school mathematics and high school teaching. The problem of the function’s maximum value in function-type application problems is also a difficulty in the function part. It is also a hot spot for the examination propositions around the country. In general, 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, which is easily overlooked by the students. The following enumerates several examples to illustrate.