我们在玩走迷宫游戏时,有时会发现,根据要求从入口找出路,往往会走入死路,如果反过来,从出口向入口走,却能很快走到出发点。数学中有些问题的解答,就像走迷宫一样,需要我们根据题意,从所给的结果出发,抓住逆运算关系,由后向前一步步倒着分析推理,逐步靠拢已知条件,直到问题得到解决。这种思考问题的方法,通常我们把它叫做倒推法。 When we play maze games, we sometimes find that finding a way out of an entrance upon request often leads to a cul-de-sac and, if on the contrary, going from an exit to an entrance, it quickly reaches the point of departure. The solution to some problems in mathematics, just like the maze, requires that we, starting from the given results, grasps the relation of the inverse operation, and from the backward to the previous step backward analysis and reasoning, and gradually approaches the known conditions until The problem is solved. This method of thinking about the problem, usually we call it the pushback method.