等量就是相等的数量。包含有三方面的含义:性质相同;单位相等;量值相等。探求等量关系是布列方程的关键。只有在审清题意的基础上认真分析数量关系,并根据具体问题采用适当的方法探求等量关系,才能顺利地列出方程(方程组)。探求等量关系的方法甚多,本文仅就最常用的几种方法,略举数例矛以说明。一、辨识不变量应用题的数量中,有些是变量,有些是不变量,它们往往混杂在一起。我们在分析数量关系的时候,要善于在事物的变化运动过程中把握不变量,着力抓住不变量这个“牛鼻子”,等量关系自然就出来了。如初中代数第一册第138页的例题:例1 某生产队,用含氨0.15％的氨水进行油菜追肥,现有含氨16％的氨水30斤,配制时需要加水多少斤?分析:这是一道溶液配制问题。在溶液问题中,有三个基本数量,即溶液、浓度、溶质。三者间的关系是 The same amount is the same amount. Contains three aspects of the meaning: the same nature; equal units; equal value. Seek the same amount of relations is the key to the Bray equation. The equation (system of equations) can be listed only if the relationship of quantity is carefully analyzed on the basis of the examination questions and the appropriate method is used to explore the equivalence relations according to specific problems. There are many ways to explore the relationship of the same amount, this article only on the most commonly used several methods, to name a few spears to illustrate. First, the identification of invariants The number of application questions, some variables, some are invariant, they are often mixed together. When analyzing the quantitative relationship, we must be good at grasping the invariants in the process of changing things, and strive to seize the “cow nose” of invariants. The relations of equivalence will come out naturally. Such as junior high school algebra first book page 138 of the example: Example 1 a production team, containing ammonia 0.15% ammonia rapeseed fertilizer, the existing ammonia 16% ammonia 30 kg, the preparation of the need to add water, how many pounds? Analysis: Is a solution preparation problem. In solution, there are three basic numbers, solution, concentration, and solute. The relationship between the three is