设<img src="https://static.zxtiku.com/wangke/imgs/topic/6cc9bd8ce7dc629be64c6b9c647de1d6.png"/>，<img src="https://static.zxtiku.com/wangke/imgs/topic/2ae46b5e3cfbb97afe0bf222ec8d711c.png"/>，<img src="https://static.zxtiku.com/wangke/imgs/topic/9791c4f811a00bbaef69c3ded58da3e2.png"/>为集合，若<img src="https://static.zxtiku.com/wangke/imgs/topic/43b73cc8fbfc268cf18e67cc70f9d1dd.png"/>且<img src="https://static.zxtiku.com/wangke/imgs/topic/cf3a0540ded4bfe256c1da349399d69c.png"/>，则<img src="https://static.zxtiku.com/wangke/imgs/topic/97c3e6ed74335fe000c87da40cf5c9b4.png"/>。