运用基本不等式(a+b)/2≥(ab)~(1/2)(a>b,b>0)求函数的最值(值域)是一种常用的、重要的方法,而处理好“一正、二定、三相等”这关键的三步又是用好基本不等式的保证.第一步(一正):基本不等式成立的前提条件是各项恒为正,因此首先要判断运用基本不等式的两项是否为 Using the basic inequality (a+b)/2≥(ab)~(1/2)(a>b,b>0) to find the function’s maximum value (value range) is a common and important method, and processing The key three steps of “good, two, three phase, etc.” are the guarantees for the use of basic inequalities. The first step (one positive): The prerequisite for the establishment of basic inequalities is that each constant is positive, so first To determine if the two items using the basic inequality are