“是否存在”问题是指:依据已知条件,判别某种数学对象是否存在,因此这类题目没给出结论,由解答者去探索和确定,它的解法是:假设存在,直接推断,通过推理或计算,若推出合理的结果,则先前假设成立对象存在;若推出矛盾,则否定先前假设,对象不存在.一般地说,有两种情况,现举例说明. The question of whether there is a problem means that whether or not a mathematical object exists according to known conditions, so no conclusion is drawn from such questions, and the solution is as follows: the hypothesis exists and is directly inferred , By reasoning or calculation, if the reasonable result is introduced, the previous hypothesis assumes the existence of the object, and if the contradiction arises, the previous assumption is negated and the object does not exist. Generally speaking, there are two kinds of situations, which are illustrated as examples.