基本不等式:1/2(ab)≤(a+b)/2(其中a≥0,b≥0)当且仅当a=b时等号成立,当1/2(ab)=(a+b)/2,此时即1/2(1/2a-1/2b)2=0,可看出a=b.a=b一方面可看作不等式成立的特殊情况,另一方面也可看作恒等式成立的条件.基本不等式等号成立的条件有两个:①两数非负,②两数相等,这就说明基本不等式等号成立对条件有着较强的要求.反过来如果基本 The basic inequality: 1/2 (ab) ≤ (a + b) / 2 (where a ≥ 0, b ≥ 0) Equal sign holds if ½ (ab) = (a + b) / 2, 1/2 (1 / 2a-1 / 2b) 2 = 0 at this time, we can see that a = ba = b can be regarded as a special case of inequality on the one hand, There are two conditions for the establishment of identity inequality: (1) two numbers are non-negative and (2) two numbers are equal, which means that the establishment of basic inequality has strong requirements on conditions, and vice versa