求多元函数极限时应注意函数的定义域

Can We Change the Domain of Definition of the Function of Several Veriables When Calculating Its Limit

求多元函数极限时,函数的定义域只能扩大而不能缩小。否则有可能导致错误结果。

When we calculate the limit of the function of several variables,the domain of definition of the function can be expanded insteat of being reduced.Or it is possible to result in mistakes.