解决数学问题的思维过程，一般是从正面入手，即从已知条件出发，经过正确的推理和运算得出结论．但有时只从正面考虑会受阻，问题难以解决，这时若逆向思维，从反面思考问题也许能找到解决问题的办法．下面列举实例谈谈几种常用的方法．１逆推法按题设的相反顺序进行推理... The thinking process to solve mathematics problems is generally started from the front, that is, starting from the known conditions, and through the correct reasoning and calculations to draw conclusions. However, sometimes the only consideration is that it is hindered and the problem is difficult to solve. At this time, if thinking backwards, thinking from the wrong side may solve the problem. Here are examples to talk about several common methods. 1 Inverse reasoning in the reverse order of the questions...