直线与圆锥曲线有无公共点或有几个公共点的问题,实际上是研究它们组成的方程是否有实数解和实数解的个数问题,此时要注意用好分类讨论和数形结合的思想方法.在用代数法研究直线与圆锥曲线的位置关系时,通常将直线方程和曲线方程联立,根据判别式Δ研究二次方程解的个数,但是在 The problem of whether there is a common point or several common points between a straight line and a conic curve is actually to study whether the equations of their composition have real number solutions and real number solutions. At this time, we should pay attention to using classification discussion and number combination Method of thinking.When algebraic method is used to study the relationship between the linear and the conic, we usually combine the linear equation with the curve equation, and study the number of the quadratic equation according to the discriminant Δ, but in the