函数与导数的交汇问题经常出现在压轴题(包括客观题和主观题中的压轴题)位置.解决这类问题时,往往会遇到某些难以确定的根、交点、极值点或难以计算的代数式,这时,不妨先设它为某字母,再利用其满足的条件式进行整体代换,以达到消元或化简的效果.下面通过实例,介绍几种具体的“设”的方法来解决这类难题. The intersection of functions and derivatives often occurs in the position of the finale (including the finale of the objective and subjective questions), and some difficult to determine roots, intersections, extreme points or difficult to calculate Of the algebraic, then, it may wish to set it as a letter, and then use the conditions to meet the overall substitution, in order to achieve the elimination or simplification effect. The following examples, introduce several specific “set” Method to solve such problems.