存在性问题是探索型问题中的一种典型性问题.存在性问题探索的方向是明确的.探索的结果有两种:一种是存在;另一种是不存在.一种方法是直接求解法,就是直接从已知条件人手,逐步试探,求出满足条件的对象,使问题得到解决的解法;另外一种方法是假设求解法,就是先假设结论存在,再从已知条件、定义、定理或公理出发,进行演绎推理;若得到和题意相符合的结论,则假设成立,结论也存在; Existence problem is a typical problem in the exploration-type problem.Explore the direction of existential problems exploration is clear.Explore the results in two ways: one is existence and the other is non-existence.One method is to solve directly Law, is directly from the known conditions of manpower, and gradually explore, find the object to meet the conditions, the problem is solved solution; another method is to assume that the solution is to assume the existence of the first known from the known conditions, definitions, Theorem or axiom, deductive reasoning; if the conclusion is consistent with the inscription, the hypothesis is established, the conclusion also exists;