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((x+1)(1x)e)xProgrammer

difficulty advanced
 Jun 22, 2015

Best Answer 

 #1
avatar+33657 
+10

Limit

.

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 Jun 22, 2015
 #1
avatar+33657 
+10
Best Answer

Limit

.

Alan Jun 22, 2015
 #2
avatar+118703 
+5

Thank you Alan,

How did you do the initial expansion?  What kind of an expansion is that?

 Jun 22, 2015
 #3
avatar+33657 
+5

I just used Mathcad to tell me Melody!  I'll see if I can derive it.

.

 Jun 22, 2015
 #4
avatar+118703 
0

Thanks Alan but worry too much, I don't understand expansions much.   :(

I only know the binomial expansion.

I just wondered :/

 Jun 22, 2015
 #5
avatar+33657 
+5

Here's a derivation explicitly using the binomial expansion:

 

 limit:

.

 Jun 22, 2015
 #6
avatar+118703 
0

Thanks Alan,

I can follow most of that but you lost me at     O(x2)     and what happened to all the other powers of x?

 

Only answer is you feel enthused because this stuff is really over my head.  I couldn't reproduce it.  :(

 Jun 22, 2015
 #7
avatar+33657 
+5

Rather than writing all the other terms involving x2x3 etc. I've written O(x2), meaning terms of order x2 and smaller ("smaller" because we are going to make x go to 0, so x4, x3 etc. are going to be smaller than x2). The important thing is that all these other terms will be multiples of xn, where n>1, so that when they are divided by x they are still mutiples of powers of x and hence vanish in the limit as x tends to 0.

.

 Jun 22, 2015
 #8
avatar+118703 
0

Thank you Alan,

I shall think on this :)

 Jun 22, 2015

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