Proving (1+x)^n approaches 1 + nx when x goes to zero

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Homework Help Overview

The discussion revolves around the mathematical expression \((1+x)^n\) as \(x\) approaches zero, specifically exploring its behavior and proving that it approaches \(1 + nx\). The subject area is calculus, focusing on limits and approximations.

Discussion Character

  • Exploratory, Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants discuss various methods for proving the statement, including epsilon-delta definitions and mathematical induction. Some suggest using the binomial expansion and the Binomial Theorem, while others question the rigor of the statement and propose alternative interpretations involving tangents and first-order approximations.

Discussion Status

The conversation is ongoing, with participants offering different perspectives on how to approach the proof. Some guidance has been provided regarding the use of binomial expansion and the need for rigor in defining the statement, but no consensus has been reached on a specific method or interpretation.

Contextual Notes

There is a noted uncertainty regarding the rigorous definition of the statement being proved, as well as the appropriateness of various proof techniques mentioned by participants.

U.Renko
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Homework Statement


I've heard this affirmation in an gravitation lecture. I thought it was interesting and decided to check it out. It turns out to be true so I decided to prove it.

I'm not a mathematician so proving stuff is not my department. Still I try to do some proofs just for fun. I hope I don't make your eyes bleed or something.


Homework Equations


\lim_{x \rightarrow 0} (1 + x)^n


The Attempt at a Solution


I'm not sure if I should try prooving by epsilon-delta or by mathematical induction (if that is even possible)
I did try by mathematical induction but it didnt look convincing

How would you do it?
 
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\lim_{x \to 0} (1 + x)^n

Apply binomial expansion to this equation and then the concept of limits.
 
Try Binomial Theorem.

While it is correct to say {(1+x)}^n \approx 1+nx for sufficiently small x, the actual limit of the expression as x tends to zero is simply 1.
 
It's impossible to prove this until you rigorized what the statement means.

I think the best rigorous version of this statement is that y=1+nx is the tangent line of y=(1+x)n at the point x=0.

Or, it could mean

\lim_{x\rightarrow 0} \frac{(1+x)^n-(1+nx)}{x}=0

which means that the functions are equal up to first order.

Try to prove these two statements.
 

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