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下面这道题曾从几种数学资料上碰到过。题已知4x+5y+9z=36,其中x、y、z均为非负数,试求x+y+z的最值。这本是一道很简单的题目,但很多人由于只想到如何去运用与不等式内容有关的那些“技巧”,反而难于作答了,有些人拼凑出了答案,但写不出有说服力的解题过程,实际上,这道题的解答只用到非负数的概念。
The following question has been encountered from several mathematical data. The problem is known as 4x+5y+9z=36, where x, y and z are all non-negative numbers. Try to find the best value for x+y+z. This is a very simple topic, but many people just think of how to use the “trick” related to inequality content, but it is difficult to answer, and some people piece together the answer, but can not write persuasive problem solving In fact, the solution to this question only uses the concept of non-negative numbers.