设函数<img src="https://static.zxtiku.com/wangke/imgs/topic/c691c8ec89405f0469a0a5fa27ac207e.png"/> (<img src="https://static.zxtiku.com/wangke/imgs/topic/f62313eed9fcd85b9f20599ff39bf872.png"/> 和<img src="https://static.zxtiku.com/wangke/imgs/topic/dd718b47bef42914a02103e703245a18.png"/> 为常数)在<img src="https://static.zxtiku.com/wangke/imgs/topic/27e302f287d522907a6f937082a8e4f2.png"/> 和<img src="https://static.zxtiku.com/wangke/imgs/topic/36162561bcd558a20186c105408e3fff.png"/> 处取得极值,则()