有关一元二次方程根的问题,不少学生总习惯于利用韦达定理求解,其实,要视具体情况而定,有的题目只需利用根的定义,有的题目只需利用韦达定理,而有的题目则需将二者结合运用.如果运用恰当,将事半功倍,出奇制胜. 一、直接运用根的定义 Regarding the problem of the root of one yuan quadratic equation, many students are always accustomed to using Vedic’s theorem to solve it. In fact, depending on the specific circumstances, some problems only need to use the definition of the root, and some problems only need to use the Vedic theorem. Some topics require the combination of the two. If used properly, they will do more with less.