Prove that the lim as x goes to a of sqrtx = sqrta

  • Context: Undergrad 
  • Thread starter Thread starter apiwowar
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Discussion Overview

The discussion revolves around proving the limit \(\lim_{x \to a} \sqrt{x} = \sqrt{a}\). It involves mathematical reasoning and the application of epsilon-delta definitions in calculus.

Discussion Character

  • Mathematical reasoning

Main Points Raised

  • One participant requests help in proving the limit.
  • Another participant suggests starting with the identity \(\sqrt{x} - \sqrt{a} = \frac{x - a}{\sqrt{x} + \sqrt{a}}\) as a key step in the proof.
  • A third participant emphasizes the importance of using LaTeX for clarity in mathematical expressions and reiterates the limit statement using LaTeX formatting.
  • A later reply outlines the epsilon-delta definition of limits, stating that to prove the limit, one must show that for every \(\epsilon > 0\), there exists a \(\delta > 0\) such that if \(|x - a| < \delta\), then \(|\sqrt{x} - \sqrt{a}| < \epsilon\).

Areas of Agreement / Disagreement

Participants express different approaches to the proof, with no consensus on a single method or resolution of the proof itself.

Contextual Notes

The discussion does not resolve the mathematical steps required to complete the proof, and assumptions regarding the definitions of limits are not explicitly stated.

apiwowar
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can i get some help on proving this limit?
 
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start with
sqrt(x)-sqrt(a)=(x-a)/(sqrt(x)+sqrt(a))
 
I think it would be very helpful if you guys used latex

The question should be

Proove that [tex]\lim {x \rightarrow a} \sqrt{x} = \sqrt{a}[/tex]

And the first reply should be

start with
[tex]\sqrt{x}-\sqrt{a}=\frac{x-a}{\sqrt{x}+\sqrt{a}}[/tex]

For basic things like this, latex only takes about a minute to learn and it VERY much easier to read :)
 
In order to prove that "[itex]\lim_{x\to a}\sqrt{x}= \sqrt{a}[/itex], you need to prove that "Given [itex]\epsilon> 0[/itex], there exist [itex]\delta> 0[/itex] such that if [itex]|x- a|< \delta[/itex] then [itex]|\sqrt{x}-\sqrt{a}|< \epsilon[/itex]".

Start from the second inequality and show (using the above hint) that you can find such a [itex]\delta[/itex].
 

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