在解析几何中，公式表示点（x0，y0）到直线ax＋by＋c=0的距离．在代数中，灵活运用这一公式的不等变形，解证一类不等式或求函数值域（最值）及变量取值范围等，常能收到形象直现、化繁为简的效果．下面给出三种不等变形，并分别举例说明其应用．它的几何意义是：直线l：ax＋b In analytical geometry, the formula expresses the distance from the point (x0, y0) to the line ax+by+c=0. In algebra, the unequal deformation of this formula can be flexibly used to solve a type of inequality or to find the range (value) of the function and the range of values ​​of the variable. It can often receive the effect of image straightforwardness and simplicity. The following three types of unequal deformations are given and examples are given for their application. Its geometric meaning is: Line l:ax+b