一元二次方程根与系数的关系,是中考命题的一个热点.一般单独考查这部分知识的命题多以填空题、选择题的形式出现,将其与解三角形、几何、二次函数等知识综合起来考查时,常以解答题的形式出现在难度系数较大的压轴题中.本文精选近几年几道中考题,分类例谈它的运用.一、求代数式 The relationship between the root and the coefficient of the quadratic equation of one yuan is a hot point of the proposition of the examination. Generally, the propositions that examine this part of the knowledge are often filled in with the form of a blank-filling question or a multiple-choice question, and are combined with the knowledge of solving triangles, geometry, and quadratic functions. When we look up, we often appear in the form of answers to questions in the finale of the larger difficulty degree. This paper selects several intermediate examination questions in recent years, and discusses its application by classification. First, the algebraic expression