如果<img src="https://static.zxtiku.com/wangke/imgs/topic/e80a8f794a39bcc0eb7a239c12ae3a42.png"/>在点<img src="https://static.zxtiku.com/wangke/imgs/topic/d72cb01274a6e9be4ae0f8340563bede.png"/>处连续，那么<img src="https://static.zxtiku.com/wangke/imgs/topic/92b066c58b3f3f2a653cd7be3bf0f970.png"/>在<img src="https://static.zxtiku.com/wangke/imgs/topic/d72cb01274a6e9be4ae0f8340563bede.png"/>处