应用极为广泛的韦达定理,是初中数学中一个充满活力的定理。近几年有部分省市自治区,把它作为中考热点。因而有必要熟悉并掌握该定理的多种用法,以提高解题能力。1 求一元二次方程根的对称式的值 The widely used Vedic theorem is a dynamic theorem in junior high school mathematics. In recent years, some provinces, municipalities and autonomous regions have taken it as a hot spot for the examination. Therefore, it is necessary to be familiar with and master the various uses of the theorem in order to improve the ability to solve problems. 1 Find the Symmetrical Value of the Root of a Quadratic Equation