limit (x→0+) (sinx)^x?

2016-07-07 9:09 am

回答 (1)

2016-07-07 10:57 am
✔ 最佳答案
Question:
lim(x→0⁺) sinˣx

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Soultion:
lim(x→0⁺) sinˣx
= lim(x→0⁺) (sin x)ˣ
= e^[ ln lim(x→0⁺) (sin x)ˣ ]
= e^[ lim(x→0⁺) x ln(sin x) ]

= e^{ lim(x→0⁺) ln(sin x) / (1/x) } ...... [ - ∞/∞ ]
= e^{ lim(x→0⁺) [(cos x)/(sin x)] / (-1/x²) } ...... [ Using L'Hôpital's rule ]

= e^[ - lim(x→0⁺) (x cos x) (x / sin x) ]
( As x→0⁺, lim (x / sin x) = 1 )
= e^[ - (0) (1) ]
= 1

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L'Hôpital's rule ( 羅必達法則 )

If lim(x→c) f(x) = lim(x→c) g(x) = 0 or ±∞ and g'(x) ≠ 0,
then lim(x→c) f(x) / g(x) = L

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                                           20160707
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收錄日期: 2021-04-11 21:28:06
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20160707010954AASjuT2

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