高考中导数是各省市每年考查的热点,通过大量的复习后,学生往往还是似是而非,尤其是导数大题中的第2小题得分甚少.其实通过反思会发现,好多情况下导数的考查背景就是三个一元二次的关系,只要搞清楚三者之间的关系,问题往往会迎刃而解.1一元二次方程根的分布导数考查的知识背景.例1若x~2+mx+2m+5=0有两个不相等的实根,求实数m的范围.分析x~2+mx+2m+5=0有两个不相 The mid-level derivative of the college entrance examination is the hot spot of each province and city every year. After a lot of review, the students are often plausible, especially the second item in the derivative topic. There are very few scores. In fact, through reflection, it will be found that in many cases, the background of the derivative examination It is the relationship between three unary quadratic relations. As long as one understands the relationship between the three, the problem will often be easily solved. 1 Background knowledge of the derivative of the root of a quadratic equation. Example 1 If x~2+mx+2m+5 =0 There are two unequal real roots and the range of the real numbers m. Analysis of x~2+mx+2m+5=0 has two phases