为了说明某一结论是正确的,不从正面直接说明,而是通过证明它的反面是错误的,从而判定它本身是正确的方法,叫“反证法”。对于某些从正面难以解答的数学题,采用反证法常常收到出奇制胜的效果。 In order to show that a certain conclusion is correct, it is not directly explained from the front, but is judged to be correct in its own right by proving its opposite, called “counter-evidence.” For some mathematic questions that are difficult to answer from the front, we often receive surprising results by using the law of proof.