Understanding Multivariable Limits: Solving with Factoring Methods

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Homework Help Overview

The discussion revolves around understanding the factoring methods used in solving multivariable limits, specifically focusing on the manipulation of expressions involving square roots and variables. Participants are examining how terms in the numerator of a function are transformed during the factoring process.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Problem interpretation

Approaches and Questions Raised

  • Participants are questioning how the term -x can be transformed into sqrt(x) during factoring. There are discussions about the validity of separating terms under square roots and the implications of negative signs in the expressions.

Discussion Status

The conversation is ongoing, with participants exploring different interpretations of the factoring process. Some have offered insights into the mathematical properties of square roots and exponents, while others are seeking further clarification on specific steps in the manipulation of the expressions.

Contextual Notes

There is an emphasis on ensuring that variables x and y are non-negative for the discussed manipulations to be valid. Participants are also noting discrepancies in the original problem setup, which may affect the understanding of the factoring process.

guyvsdcsniper
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Homework Statement
Find the limit
Relevant Equations
lim(x,y)->(0,0)

I do not understand how they got the -x in the numerator to turn into a sqrt(x) when factoring to solve this multivariable function. Could some help me understand?
 
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That is not the same problem. There is a sign difference in the first term of the numerator.
 
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FactChecker said:
That is not the same problem. There is a sign difference in the first term of the numerator.
I missed that. I need to edit my post. The 1st problem in the 2nd image is what I am questioning. How did they get -x to become sqrt(x)?
 
quittingthecult said:
I missed that. I need to edit my post. The 1st problem in the 2nd image is what I am questioning. How did they get -x to become sqrt(x)?
In the work shown, ##\sqrt{xy} - x## was factored into ##\sqrt x(\sqrt y - \sqrt x)##.

Clear?
 
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Mark44 said:
In the work shown, ##\sqrt{xy} - x## was factored into ##\sqrt x(\sqrt y - \sqrt x)##.
Yea that is what's getting me. I get separating sqrt(xy) into sqrt(x)*sqrt(y). I just don't see how the -x turns into sqrt(x) when factoring.
 
Mark44 said:
In the work shown, ##\sqrt{xy} - x## was factored into ##\sqrt x(\sqrt y - \sqrt x)##.

Clear?
Oh wait. The -x is technically -x^1 and sqrt of x is technically x^1/2. so if pull a x^1/2 you are left with a x^1/2. Is that correct?
 
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quittingthecult said:
Oh wait. The -x is technically -x^1 and sqrt of x is technically x^1/2. so if pull a x^1/2 you are left with a x^1/2. Is that correct?
Why over-complicate things?
quittingthecult said:
I get separating sqrt(xy) into sqrt(x)*sqrt(y).
But you don't get separating sqrt(xx) into sqrt(x)*sqrt(x)? Edit: or ## \dfrac {x}{\sqrt x} = \sqrt x ##?

Note that we must be sure that x (and y) are non-negative for these manipulations.
 
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quittingthecult said:
Oh wait. The -x is technically -x^1 and sqrt of x is technically x^1/2. so if pull a x^1/2 you are left with a x^1/2. Is that correct?
Yes. You could also try multiplying out the factorization @Mark44 showed you and see that you recover what you started with.
 

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