Limit of a squareroot combination.

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SUMMARY

The limit of the expression sqrt(x + sqrt(x)) - sqrt(x) as x approaches infinity is determined using conjugate multiplication. By multiplying the numerator and denominator by the conjugate, the expression simplifies to sqrt(x) / (sqrt(x + sqrt(x)) + sqrt(x)). As x approaches infinity, the term sqrt(x)/x tends to zero, leading to the final limit of 1/2. This method effectively demonstrates the application of limits in calculus.

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  • Understanding of limits in calculus
  • Familiarity with conjugate multiplication
  • Knowledge of square root properties
  • Basic algebraic manipulation skills
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Students studying calculus, particularly those focusing on limits and algebraic manipulation techniques. This discussion is beneficial for anyone seeking to improve their understanding of limit evaluation methods.

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Homework Statement


find lim x---> infinity
sqrt(x + sqrt(x)) - sqrt(x)


Homework Equations


Conjugate multiplication.



The Attempt at a Solution


Ok so i know this is probably very easy yet it confuses me.
Im guessing youd need to multiply the numerator & denominator by the conjugate of the expression, and then work the expression into a form where all the x terms are denominators of a fraction so that as they approach inf, the fraction approaches 0.

(sqrt(x + sqrt(x)) - sqrt(x))(sqrt(x + sqrt(x)) + sqrt(x))
/ sqrt(x + sqrt(x)) + sqrt(x)

(x + sqrt(x) +sqrt(x)sqrt(x + sqrt(x)) -sqrt(x)sqrt(x + sqrt(x)) - x)
/ (sqrt(x + sqrt(x)) + sqrt(x))

sqrt(x)
/ (sqrt(x + sqrt(x)) + sqrt(x))

this is as far as i get, any help would be appreciated.

P.s: does this forum have a way of writing maths in a bit more easily comprehendable form?
 
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There should be a guide to using latex somewhere around here.

[tex]\sqrt{x+\sqrt{x}}=\sqrt{x} \sqrt{1+\sqrt{x}/x}[/tex]

If you click on that it should pop up a window showing what I typed in. Sorry, I'm not all that good at it. By the way, that's your next step as well.
 
Last edited:
All right so we have:
sqrt(x)
/ (sqrt(x + sqrt(x)) + sqrt(x))

sqrt(x)
/ (sqrt(x) sqrt(1+sqrt(x)/x) + sqrt(x)

1 / sqrt(1+sqrt(x)/x) + 1

sqrt(x)/x tends to zero when x ---> infinity

1 / sqrt(1) +1

1/2

K that makes sense now, thank you.
And sry bout the lack of latex notation, il look into it for next time!
 

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