二次函数的一般表达式为f(x)=ax2+bx+c(a≠0),配方后可以表示为f(x)=a(x-h)2+k,如果它的图象与x轴有两个不同的交点x1,x2,还可表示为f(x)=a(x-x1)(x-x2).这样二次函数就有了三种不同的表达形式,在不同的问题中选择合适的表达形式对于快速准确地解决问题有着至关重要的作用.本文就f(x)=a(x-x1)(x-x2)的应用作一下探讨. The general expression of the quadratic function is f(x)=ax2+bx+c(a≠0), and the formula can be expressed as f(x)=a(xh)2+k if its image is along the x-axis. There are two different intersections x1, x2, which can also be expressed as f(x)=a(x-x1)(x-x2). This way, the quadratic function has three different forms of expression, in different problems. Choosing the appropriate form of expression plays a crucial role in quickly and accurately solving the problem. This paper discusses the application of f(x)=a(x-x1)(x-x2).