最值问题求解时高中数学的一个重要知识内容,它的重要性不仅体现在试题背景的多样性上,也体现在试题解法的多样性上,常与其他知识进行综合,如与函数、不等式、向量及圆锥曲线等内容相结合,常常让同学们解题时望而生畏.但无论是利用均值不等式求最值,还是利用函数的单调性及换元等其他方法求解最值问题,其实是万变不离其宗的,虽然形式上变化多端,但其本质或目的不变.本文就可以通过转化,化为一元二次函 The value of the problem solving a high school mathematics an important knowledge content, its importance not only reflected in the diversity of the test background, but also reflected in the diversity of test solution, often integrated with other knowledge, such as with the function, inequality, Vector and conic curve, etc., often make students daunting when solving the problem.However, whether it is to use the mean value inequality for the most value, or the use of monotonic function and change the yuan and other methods to solve the most value problem, in fact, is inseparable Although its form varies in a variety of ways, its essence or purpose remains unchanged.This paper can be transformed into a quadratic