数学竞赛中,常出现求分式最值的题型,而这类题目学生往往感到无法入手,现摘取几题分析其解法.例1当x变化时,分式3x~2+6x+5/1/2x~2+x+1的最小值是____.分析分式的分子,分母中都含有字母x,不便讨论,我们可以通过同分母通分的逆运算将分式中分子的字母化去,使得分式中仅有分母含有字母,以此确定分式的最值. Mathematical competition, often appear the most value of the question type, and students often feel like this topic can not start, now extract a few questions to analyze its solution. Example 1 When x changes, the fractional 3x ~ 2 + 6x +5 / 1 / 2x ~ 2 + x + 1 is the smallest ____. Analysis of fractional molecules, the denominator contains the letter x, inconvenience to discuss, we can through the denominator of the inverse of the numerator of the numerator of the letter To go, so that only the fractional letter contains the denominator, in order to determine the fractional value.