我们解题的习惯是从条件出发或对条件进行处理,获得解题方法,使问题得解.但有些题解答较繁或较难,若改变常规的习惯,按相反的思维方向思考,把结论换元,化未知为已知,获得简单方法.当待解题目的条件较繁,而结论形式简单时,可考虑这种方法.现举例说明. Our habit to solve problems is to proceed from the conditions or conditions, access to problem-solving methods to solve the problem.But some questions more complicated or difficult to answer, if the change of conventional habits, thinking in the opposite direction, the conclusion For the yuan, the unknown is known, access to simple methods.When the conditions to be solved more complicated, and the conclusion of the form is simple, you can consider this method is an example.