[考古] 97北大，資工系

看板trans_math作者wei0152019 (6V)時間15年前 (2010/06/25 19:03)推噓1(1推 0噓 3→)

留言4則, 2人參與討論串1/1

７.(a) Find the Taylor expansion of cos(x^2) at x=0. (b) Determine cos(x^2) radius of convergence. 請問(b)小題我這樣算有錯嗎? 因為沒有正確解答又覺得有點奇怪，所以請各位高手幫忙解題@@ 我的算法是： x^4 x^8 x^12 cos(x^2)= 1 +-----+-----+-----+..... 2! 4! 8! 1 --------- [2(n+1)]! (2n)! lim ------------ = lim ------------------- = 0 n→∞ 1 n→∞ (2n+2)(2n+1)(2n)! --------- (2n)! => radius of convergence = ∞ -- ※ 發信站: 批踢踢實業坊(ptt.cc) ◆ From: 118.169.41.133

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owlran

06/25 20:10, , 1^F

06/25 20:10, 1^F

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wei0152019

06/25 23:51, , 2^F

06/25 23:51, 2^F

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owlran

06/26 00:02, , 3^F

06/26 00:02, 3^F