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抽象函数是指没有给出函数的具体解析式,只给出了一些体现函数特征的式子的一类函数.由于抽象函数表现形式的抽象性,使得这类问题成为函数内容的难点之一.本文就抽象函数常见题型及解题法评析如下:一、定义域问题例1已知函数f(x~2)的定义域是[1,2],求f(x)的定义域.解f(x~2)的定义域是[1,2],是指1≤x≤2,所以f(x~2)中的x~2满足1≤x~2≤4从而函数f(x)的定义域是[1,4]评析一般地,已知函数f((?)(x))的定义域是A,求f(x)的定义域问题,相当于已知f((?)(x))中x的取值范围
Abstract function refers to a kind of function that does not give a concrete analytical expression of a function but only gives some formulas that reflect the characteristic of a function, which is one of the difficulties in the function content due to the abstraction of abstract function representation. In this paper, the abstract function common problem-solving and problem-solving method as follows: First, the domain problem Example 1 known function f (x ~ 2) domain is [1,2], and find the domain of f f (x ~ 2) is defined as [1,2], which means that 1≤x≤2. Therefore, x ~ 2 in f (x ~ 2) satisfies 1≤x ~ 2≤4 so that the function f The generalized domain of the known function f ((?) (X)) is A, and the domain of f (x) is defined, which is equivalent to the known f ((? (x)) x in the range of values