Having trouble simplifying conjugate

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    Conjugate Simplifying
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Discussion Overview

The discussion revolves around the simplification of the expression (4[(SQRT(x+2)) – (SQRT2))]/x, particularly in the context of finding a limit as x approaches 0. Participants explore different methods of simplification and their implications for solving the limit problem.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant expresses uncertainty about their simplification process after multiplying by the conjugate, arriving at 4/((SQRT(x+2)) + SQRT2).
  • Another participant suggests that the only meaningful simplification is to distribute the 4, leading to [4*sqrt(x+2) - 4*sqrt(2)]/x, and questions the utility of the conjugate method.
  • A different participant clarifies that the problem is a limit problem and mentions an estimated limit of 1.414 using a table.
  • Further replies indicate that the form 4/((SQRT(x+2)) + SQRT2) avoids the 0/0 indeterminate form when evaluating the limit at x=0.
  • One participant advises multiplying the conjugate to both the numerator and denominator, suggesting that this leads to a cancellation of x and a straightforward evaluation of the limit.
  • Another participant agrees with the previous responses, affirming that the derived form makes the limit trivial to compute.
  • There is a side discussion about the organization of questions in the forum, with some participants suggesting that related questions should be kept together for clarity.

Areas of Agreement / Disagreement

Participants generally agree on the correctness of the algebraic manipulation leading to a limit evaluation, but there is some disagreement regarding the definition of "simplified" and the best approach to take for the problem.

Contextual Notes

There are unresolved assumptions regarding the definitions of simplification and the context in which the expression is being used, as well as the implications of different forms for subsequent calculations.

ladyrae
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I am having trouble simplifying

(4[(SQRT(x+2)) – (SQRT2))]/x

I multiply the conjugate and I come up with 4/((SQRT(x+2)) + SQRT2)

I'm not sure if I'm on the right track
 
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Quite frankly, by the concept of "simplified" that I am familiar with, the only simplification of the original that is possible is simply to multiply the 4 through:

[4*sqrt(x+2) - 4*sqrt(2)]/x

"Simplified" usually means rational denominators - your multiplying by the conjugate took you in the opposite direction.

What is this for? If the problem is just to simplify the original expression, then what I gave is as far as you can go. But if you need to do something else afterward, then this "simplified" form may not be the easiest to work with. It depends on the application.
 
Actually its a limit problem I'm working on I'm having trouble with algebra.

Find the limit by analytic methods:

lim x->0 (4[(SQRT(x+2)) – (SQRT2))]/x

The first part of the problem asked me to estimate the limit by using a table and I came up with 1.414.

I am trying to multiple the conjugate...
 
ladyrae said:
I am having trouble simplifying

(4[(SQRT(x+2)) – (SQRT2))]/x

I multiply the conjugate and I come up with 4/((SQRT(x+2)) + SQRT2)

I'm not sure if I'm on the right track

Actually you've already done all the hard work. Notice that the form you now have, 4/((SQRT(x+2)) + SQRT2), no longer gives you 0/0 if you evaluate it at x=0. So you can just plug in x=0 and get the result of the limit. You'll get 4/(2*SQRT(2))=2/SQRT(2)=SQRT(2).
 
Last edited:
Did you multiply (sqrt (x+2) + sqrt (2) ) to your numerator and your denominator?
You should end up with 4(x) / [x((SQRT[x+2]) + (SQRT[2]))]
cancel an x on top and bottom. now you can plug in 0s anywhere x is (only one place)and you get
4/ (SQRT[0+2] + SQRT[2])
now what have you got?
 
whoops! mc beat me to it!
 
Master coda is right. Your derivation was correct, and in this form the limit is trivial.

(An excellent example of where "simplified" is not the form you want.)
 
ladyrae, why didn't you post this in your earlier limit thread, which you already created to get help with this problem? It's much easier to keep track of your questions if you keep them in one place.
 
sorry

sorry, i thought it would be the wrong section for an algebra question.
 
  • #10
Well, it was related to your original question about the limit, so I think it's fine to put it in the same thread. Any given problem might have parts that relate to physics, calculus, and algebra, but it's easier to follow and help you with your work if it's all together in one section.
 

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