一、知识要点1．一元二次方程报与系数的关系—韦达定理及其逆定理：若x1、x2是方程的两个根则特殊地，若X1、x2是方程的两个很，则这是韦达定理．反之，若和X2。是方投的两个很．特殊地，若，则X1和x2是方程的两个根．这是韦达定理的逆定理．初中代数课本把这两个定理统称为一 First, knowledge points 1. The relation between the one-dimensional quadratic equation and the coefficient - Weedar’s theorem and its inverse theorem: If x1, x2 are the two roots of the equation, in particular, if X1, x2 are two of the equations, then this is the Weida theorem. On the contrary, if and X2. It’s a very good two. Specifically, if X1 and X2 are the two roots of the equation. This is the inverse theorem of Weida’s theorem. The junior school algebra textbook collectively refers to these two theorems as a