[DSE 2021] 大家準備好瘋狂做 數學 未呢? [5]

1001 回覆
1 Like 9 Dislike
2020-10-27 01:06:45
係, 之後h會keep decreasing, 但用呢個樣就即使h=0都唔會undefined
2020-10-27 08:22:10
可以咁做,因為S^2係continuous 所以你揾左佢等於零果點,即係果點之外的一段(或一塊)必然全大於零或全小於零,咁你take 左一個point証左就OK啦。(純concept,唔駛寫)

好喇,問題係h set 左必然係decreasing,因此你個h domain 由 1.2 r 到 0 先至成立,最好加埋呢句。(HKEAA個MS都有寫)
2020-11-04 22:55:40
2020-11-04 22:58:16
2020-11-04 23:01:30
2020-11-04 23:09:06
2020-11-04 23:30:51
2020-11-04 23:31:02
2020-11-04 23:51:14
即係一定要拆咗fractions先至sub u=x-1?
如果我未拆就sub會出:
∫(u^(2)-1)/u^(2)du = ∫1-(1/u^(2)) = u + 1/u + C = (x-1) + 1/(x-1) + C
但正確答案係 x + 1/(x-1) + C
2020-11-04 23:52:31
即係一定要拆咗fractions先至sub u=x-1?
如果我未拆就sub會出:
∫(u^(2)-1)/u^(2)du = ∫1-(1/u^(2))du = u + 1/u + C = (x-1) + 1/(x-1) + C
但正確答案係 x + 1/(x-1) + C
2020-11-04 23:57:39
2020-11-05 00:01:58
其實你計到 (x+1)+1/(x+1)+C 咪啱囉
你想似個答案咪寫 x+1/(x+1)+C’
2020-11-05 00:08:30
唔係呀巴打
Correct Ans: x + [1/(x-1)]+ C
My Ans: (x-1) + [1/(x-1)] + C
2020-11-05 00:08:44
1/(x-1)* sorry 總之你其實計啱,啲constant可以加加減減
2020-11-05 00:11:31
哦!!! 即係將個-1擺落個C度, 出C’ = C-1 咁樣?
2020-11-05 00:11:38
Sorry, 我冇追post睇清楚
但你真係計啱呢

(x-1) + [1/(x-1)] + C
=x + [1/(x-1)]+ (C-1)
=x + [1/(x-1)]+ C‘ (for another arbitrary constant C’=C-1)
2020-11-05 00:12:05
Yes 你明白了
2020-11-05 00:12:58
明白晒, 唔該晒巴打, 我自己concept唔清唔好意思
2020-11-05 00:14:29
2020-11-05 00:16:46
2020-11-05 00:21:57
學校教緊3D trigo 我覺得難在佢變化好大 有咩方法可以master 3D trigo? 同依家啲section b 題目係咪都係3D trigo?
2020-11-05 00:30:13
做pp 就會發現萬變不離其宗
主要分三類
1. 三面體/四面體 (極少information都要搵到volume, 要記佢哋特別嘅properties)
2. 摺紙擺喺枱度 (extend啲線搵required angle between 2 planes)
3. 太陽&影子 (溝埋bearing出, DSE暫時未出過)
2020-11-05 01:13:33
一樣啫,個減1會被個constant C食咗㗎嘛
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