同学们在探求某些数学问题的解法时,常常感到思路受阻,不知从何处入手.这时不妨将问题退回到较为简单易解的情形,从中寻找出问题的本质属性和变化规律,获得思维灵感,从而使原问题得到解决,这就是“以退求进”的数学思想.请看下面两例. When students are searching for solutions to certain mathematical problems, they often feel that their ideas are blocked and they do not know where to start. At this time, they may wish to return the problem to a more simple and easy-to-understand situation, in order to find out the nature of the problem and the law of change, and obtain the thinking. Inspiration, so that the original problem is solved, this is the “retreat advance ” mathematical thinking. Please see the following two examples.