Trivial limit ( 1 - (-x)^n ) / 1 + x


by davitz
Tags: limit, trivial
davitz
davitz is offline
#1
Jun10-12, 04:15 AM
P: 2
1. The problem statement, all variables and given/known data

lim ( 1 - ( - x ) ^ n ) / ( 1 + x ) as n -> infinity

2. Relevant equations

I can't understand why this equals to 1 / ( 1 + x ) (No matter what power of " n " was x e.q: x ^ 2n or x ^ ( n ^ 2 )

3. The attempt at a solution

I have no clue what rule to apply. I thought it might be a case of using the lim ( 1 + 1 / n ) ^ n to get to " e " but this seems like a non-sense in this case.
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Infinitum
Infinitum is offline
#2
Jun10-12, 04:25 AM
P: 836
I think you first need to have a condition on x before that is true.

0 < x < 1, right?

If so, anything between 0 and 1 raised to a power of infinity will tend to 0, as it gets smaller with each successive multiplication.

[tex]\lim_{n\to \infty} x^n = 0[/tex]

where -1<x<1
davitz
davitz is offline
#3
Jun10-12, 04:28 AM
P: 2
Thank so much for the reply! Yes, x > -1 and x < 1 or -1 < x < 1 and now I understand why this is the result!

Thank you again!

Infinitum
Infinitum is offline
#4
Jun10-12, 04:32 AM
P: 836

Trivial limit ( 1 - (-x)^n ) / 1 + x


Glad to have been of help!


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