二次函数作为一类简单而又基本的函数类型,具有丰富的内涵与外延.以其为素材可以对函数的性态进行全面的分析和研究,以其为载体可以把数与形有机地融合起来,使数形结合、分类讨论、等价转化、函数与方程的思想方法得到充分的发挥,以其为纽带可以沟通函数、方程、不等式、数列和 As a simple and basic function type, quadratic function has a rich connotation and extension. Using it as a material can comprehensively analyze and study the behavior of a function. As a carrier, it can organically integrate numbers and shapes. Together, the ideas and methods of combination of number and shape, classification and discussion, equivalent transformation, functions and equations are fully utilized, and they can be used as a link to communicate functions, equations, inequalities, and sequences.