函数的值域是函数概念的一个重要组成部分，在研究函数的图象、性质及实际问题中非常有用．求函数的值域的方法很多，如常说的观察法、配方法、图象法、判别式法、换元法等等，但广大师生仍然普遍感到求函数的值域问题是教学中的一个难点．本文试图给出求函数值域问题的一个一 The value range of a function is an important part of the concept of the function and is useful in studying the image’s image, nature, and practical problems. There are many ways to find the value range of a function, such as the observation method, the matching method, the image method, the discriminant method, the replacement method, etc., but teachers and students still generally feel that the value of the function is a problem in teaching. difficulty. This article attempts to give a one-by-one question of function value range