抽象函数通常是指没有给出函数的具体的解析式,只给出了其它一些条件(如函数的定义域、单调性、奇偶性、解析递推式等)的函数问题,解决此类问题的方法有赋值法、递推法、反证法、类比探究法、演绎探究法等,但最主要的方法是赋值法.在抽象函数问题中,因没有给出具体的函数.仅含有抽象的函数符号,抽象的函数结构式或抽象的函数关系式,因此解决此类问题的有力手段就是赋值,巧妙赋值,可解决以下五类问题. Abstract function usually refers to no specific analytic function is given, only given some other conditions (such as the function domain, monotonicity, parity, analytic recursion, etc.) function problems to solve such problems The methods are assignment method, recursion method, inverse proof method, analogical inquiry method and deductive inquiry method, but the most important one is the assignment method.In the abstract function problem, no specific function is given.It contains only abstract function symbols, Abstract function structure or abstract function relationship, so a powerful means to solve such problems is the assignment, clever assignment, can solve the following five kinds of problems.