[線代] one-to-one and onto

看板Math作者 (無法顯示)時間14年前 (2011/05/14 22:25), 編輯推噓1(108)
留言9則, 3人參與, 最新討論串1/2 (看更多)
let D be the differentiation operator on P[3], and let S = {p屬於P[3] | p(0)=0} show that (a) D maps P[3] onto the subspace P[2], but D: P[3] -> P[2] is not one-to-one (b) D: S -> P[3] is one-to-one but not onto 請問這題該怎麼證呢? 謝謝!! -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 61.228.28.136

05/14 22:35, , 1F
(a)P[3]裡面每個只差常數的多項式都會映到同一個
05/14 22:35, 1F

05/14 22:37, , 2F
(b)P[2]中任一元素都可以積分回去唯一的P[3]元素
05/14 22:37, 2F

05/14 22:39, , 3F
上一行說錯了
05/14 22:39, 3F

05/14 22:41, , 4F
(b)S中任兩不同元素經過映射後會射到不同兩點
05/14 22:41, 4F

05/14 22:42, , 5F
(b)可以用兩式相減來證
05/14 22:42, 5F

05/14 22:43, , 6F
Kernel, image
05/14 22:43, 6F

05/14 22:45, , 7F
不過你從以前到現在問了這麼多線代問題,到了現在還
05/14 22:45, 7F

05/14 22:45, , 8F
問這類題目還蠻怪的...
05/14 22:45, 8F

05/15 00:21, , 9F
樓上+1 從以前就看到你問類似的題目了
05/15 00:21, 9F
文章代碼(AID): #1Dpf3Szz (Math)
文章代碼(AID): #1Dpf3Szz (Math)