有些数学问题,其中的可变因素往往不止一个,若所有可变因素同时变动,则不易观察。我们常常可仅让一个因素变动而其余因素暂时固定。然后,在解决了这一较为特殊的问题以后,我们又可以由局部到整体而求得整个问题的解,这就是局部变动法。局部变动法是一个重要的数学方法,现举例说明这—方法的具体运用。 Some mathematical problems, of which there are often more than one variable, if all variables change simultaneously, it is not easy to observe. Often we can make only one factor change and the remaining factors temporarily fixed. Then, after solving this more specific problem, we can find the solution to the entire problem from the part to the whole. This is the law of local changes. The Local Change Act is an important mathematical method and is an illustration of the concrete application of this approach.