零点这个概念,我们并不陌生。在初中解绝对值方程或不等式时,我们用的是零点分段讨论法;在高中解一元高次不等式时,我们用了数轴标根法。二者都与零点有关。一般来说,代数中某些需要分类讨论的问题。常借助于零点。解析几何的基本工具是代数,零点在解几讨论题中,也很有用。下面举例说明。 The concept of zero is no stranger to us. When we solve the absolute value equation or inequality in junior high school, we use the zero-point segmentation method; when we solve a high-order inequality in high school, we use the number-axis method. Both are related to the zero point. In general, some of the problems in algebra need to be discussed in the classification. Always resort to zero. The basic tool for parsing geometry is algebra, and zero is also useful in solving several problems. The following is an example.