关于曲线的凹凸性,下列说法错误的是( ).<br>· 曲线<img src="https://zk.995w.com/lqwvjeImg/fa/fa8edb9750044d9e6493a490acaa265c.png"style="width:44px;height:24px;">在定义域内是凹的.<br>· 曲线<img src="https://zk.995w.com/lqwvjeImg/aa/aa893a85abfe34fe0d7c5962e8d94a25.png"style="width:53px;height:24px;">在定义域内是凸的.<br>· 曲线<img src="https://zk.995w.com/lqwvjeImg/5d/5d29bcd7c400a6b0e92886df0b0f2efd.png"style="width:43px;height:24px;">在定义域内是凹的.<br>· 曲线<img src="https://zk.995w.com/lqwvjeImg/f5/f57f8c6c6d11b468e3b8032747e6478a.png"style="width:43px;height:24px;">在<img src="https://zk.995w.com/lqwvjeImg/f9/f9545b4675bfd766b7869850e42f379c.png"style="width:51px;height:27px;">内是凹的.