在证明一些多元不等式时 ,经常需要考虑变元的大小关系 ,于是就出现了“设ｘ≥ ｙ≥ｚ”的语句。这样设 ,会不会存在问题呢 ?先看两个已见于一些出版物的例题的证明 ,然后 ,就所设的不当之处及这样设法应具备的条件作一些论述。例 1　令ｘ、ｙ、ｚ是满足ｘ +ｙ +ｚ =1的非负实 When proving some polynomial inequalities, it is often necessary to consider the size relationship of the arguments, so the statement “set x ≥ y ≥ z” appears. In this way, will there be problems? Let us first look at the proofs of the two examples that have been found in some publications, and then make some expositions on the wrongs that have been set up and the conditions that we should try to achieve. Example 1 Let x, y, and z be non-negative realities that satisfy x + y + z =1