<p>设曲线<img src="https://learnfile.20230611.cn/learnAppQuestion/c4/78/c478fd4337a1064790785e7f8e28c75d.jpg">在点<img src="https://learnfile.20230611.cn/learnAppQuestion/72/f6/72f6edfea7568190ad01299c45f61014.jpg">处有水平的切线，则<img src="https://learnfile.202