不等式在数学的各个分支上都有应用,自然也是高考的重点,特别是在填空题中(包括解不等式、求最值)往往能够考查多种数学思想方法的灵活应用,因此这类题多以中档题或难题的形式出现,下面我们通过几例来说明。先来看一道引例:已知x,y,z为正实数,满足x-2y+3z=0,则y~2/xz的最小值是_____。本题是一道中档题,有三个未知量,因此看到题目后的第一反应是消元,关键是x,y,z中消去哪个。为使目标式y~2/xz分母简单,我们 Inequalities have applications in all branches of mathematics and are naturally the focus of entrance examinations. In particular, in the field of blank filling (including solving inequality and finding the most value), Inevitably test a variety of mathematical ideas and methods, Mid-range questions or problems in the form of the following, we will illustrate by a few examples. First look at an example: Known x, y, z is a positive real number, to meet x-2y + 3z = 0, y ~ 2 / xz minimum is _____. The title is a mid-range title, there are three unknowns, so the first reaction after seeing the title is elimination, the key is which x, y, z eliminated. In order to make the target y ~ 2 / xz denominator simple, we