[代數] 請幫我看看我做的對不對(有2題)

看板Math作者 (映雪)時間11年前 (2012/09/04 12:12), 編輯推噓1(103)
留言4則, 4人參與, 最新討論串1/1
先說聲對不起喔,過了個暑假,對代數一整個變生疏了 所以想請各位大大幫忙看一下=D" Let <(3,3)> be the cyclic subgroup of Z9xZ6 generated by (3,3) and let L be the quotient group Z9xZ6/<(3,3)>. 1. Find the order |L|. sol: |L|=|Z9xZ6/<(3,3)>|=|Z9xZ6|/|<(3,3)>| 因為 <(3,3)>={(3,3),(6,0),(0,3),(3,0),(6,3),(0,0)} 所以 |L|=9x6/6=9 --- True or false. With a reason. Let G be the group of order 40. If g 屬於 G such that g^20 =\= e (where e is the identity of G), then G is cyclic and generated by g. sol: False. 反例: Let G=Z5xZ8 and g=(0,1). Then g^8=(0,0), g^20=\=(0,0). Clearly, G=\=<(0,1)>. --- 不好意思,只是簡單的兩題,卻沒什麼把握= =" 請鞭小力一點,如果有錯或是有更好的想法請告訴我,謝謝 >口<" (晚點可能會在放一題上來= =...) -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 114.40.220.113

09/04 12:51, , 1F
Z5xZ8 是 cyclic, 無誤
09/04 12:51, 1F

09/04 16:17, , 2F
應該都對吧?(跟你一樣許久沒接觸代數的人)
09/04 16:17, 2F

09/04 19:29, , 3F
1F:雖然Z5xZ8是cyclic,但(0,1)不是generator
09/04 19:29, 3F

09/04 21:39, , 4F
2.g=(1,1) g^20=(0,4)≠e
09/04 21:39, 4F
文章代碼(AID): #1GHN-bVL (Math)