<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image063.png" alt="" align="middle">，但<img src="http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image064.png" alt="" align="middle">
函数<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image061.png" alt="" align="middle">在<img src="http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image062.png" alt="" align="middle">点处连续
函数<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image061.png" alt="" align="middle">在点<img src="http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image062.png" alt="" align="middle">处可导
函数<img src、"http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image061.png" alt="" align="middle">在点<img src="http://oss.ouchn.cn/ddzx/N601/gongxue/jjsx/img/1-2/image062.png" alt="" align="middle">处有定义