设<img src="https://static.zxtiku.com/wangke/imgs/topic/2a2a70faee332c39e5363bd03b223493.jpg"/>为群<img src="https://static.zxtiku.com/wangke/imgs/topic/94b3e9b488961be466e2e03d93670713.jpg"/>的两个正规子群. 证明:如果<img src="https://static.zxtiku.com/wangke/imgs/topic/cbc55376790178992176f4166da98ad7.jpg"/>,则对任意的<img src="https://static.zxtiku.com/wangke/imgs/topic/b14bf98e38ad4fa9b1094b7e2e091072.jpg"/>,有<img src="https://static.zxtiku.com/wangke/imgs/topic/4c0b5145004e1f2e364889a72c5f9da4.jpg"/>.