推 j19951102 : thanks~ 01/20 16:15
※ 引述《j19951102 (j19951102)》之銘言:
: f(x) = 2/(1-x^2), compute 1234th derivative of f(0)
: 直接微分似乎找不到規律? 有什麼技巧嗎?
2
f(x) = ---------
1 - x^2
1 1
= ----- + -----
1-x 1+x
n -(n+1) n -(n+1)
=> f (x) = n! * (1-x) + (-1) * n! * (1+x)
1234
所求 = f (0) = 1234! + 1234! = 2 * 1234!
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