‍设函数<img src="https://static.zxtiku.com/wangke/imgs/topic/c924f1429a5ced00951aca28d7090b87.png"/>具有连续的导数, 且<img src="https://static.zxtiku.com/wangke/imgs/topic/48fbe17be3458929995403ab1e9a3063.png"/>, 已知曲线积分<img src="https://static.zxtiku.com/wangke/imgs/topic/12950c6e2848b7393bebe24b95e0ebbe.png"/>与路径无关, 则计算积分<img src="https://static.zxtiku.com/wangke/imgs/topic/dc4280f3007166c6ef22a3592e54235c.png"/>( ).