依照题设条件,建立函数关系式,通过求极值的办法,获得正确可靠的答案,解决一些难于用文字叙述说清的题目。下面通过例子说明这种方法。例1:三个完全相同的长方体木块,把它们放在三种密度不同的液体里,木块静止时浸入液体里的情况如图一所示,甲木块大部分浸入,乙木块一半浸入,丙木块小部分浸 In accordance with the conditions set up, establish a functional relationship, through the method of seeking extremum, to obtain correct and reliable answers, to solve some difficult to use text to clarify the title of the problem. The following example illustrates this method. Example 1: Three identical cuboid blocks are placed in three liquids of different densities. The immersed liquid in the static state of the block is shown in Figure 1. Most of the blocks are immersed and half of the blocks are immersed. , small pieces of B block