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Mad Scientists Science and Mathematics discussion-- theories, arguments, citations, proofs and pudding.

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 #1 
Old 2008-09-29, 13:41
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Chicago IL USA
Default derivative question

Can somebody show me what

lim e^tanx
x->pi/2+

is please?
 #2 
Old 2008-09-29, 16:37
bobfish bobfish is offline
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Default Re: derivative question

Yes..
 #3 
Old 2008-09-29, 16:46
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Chicago IL USA
Default Re: derivative question

Sorry the title meant to say limit question.
 #4 
Old 2008-10-01, 03:29
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Chicago IL USA
Default Re: derivative question

So no one knows the answer to this question?

Lifejunkie where are you! lol
 #5 
Old 2008-10-01, 03:46
Shadout Mapes Shadout Mapes is offline
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Default Re: derivative question

just move the limit inside the exponent:

exp( lim(x-> pi/2+) tanx)

As you move from x = pi to x = pi/2 (this is what the + means right? it's been a while, i might be going in the wrong direction) tanx goes to -infinity. so now:

lim (x-> -infinity) e^x

i hope that simplifies the problem sufficiently
 #6 
Old 2008-10-01, 15:08
bobfish bobfish is offline
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Default Re: derivative question

Pi/2 has no tangent. Division by 0.
 #7 
Old 2008-10-02, 06:09
Shadout Mapes Shadout Mapes is offline
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Default Re: derivative question

Quote:
Originally Posted by bobfish
Pi/2 has no tangent. Division by 0.


Which would be the purpose of taking the limit. Although it is an important distinction that a one-sided limit is usually necessary in the case where the denominator approaches zero for the limit to be defined.
 #8 
Old 2008-10-02, 20:11
SelfAdjoint SelfAdjoint is offline
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Default Re: derivative question

Since the exponential function is a continuous function, you can take the limit inside the exponent. Which gives you a divergent limit. Problem solved; the limit doesn't exist. If the limit approaches from the other side of pi/2, the limit is zero.
 
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