Limit of a squareroot combination.

In summary, the speaker is trying to find the limit as x approaches infinity of the expression sqrt(x + sqrt(x)) - sqrt(x). They attempt to use conjugate multiplication to simplify the expression and get it into a form where all the x terms are denominators of a fraction. They get as far as 1/2 as the final answer. They also inquire about using LaTeX notation on the forum.
  • #1
Dissonance in E
71
0

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?
 
Physics news on Phys.org
  • #2
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:
  • #3
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!
 

FAQ: Limit of a squareroot combination.

What is the definition of a limit?

The limit of a function is the value that the function approaches as the input approaches a given value or point.

How do you find the limit of a squareroot combination?

To find the limit of a squareroot combination, you can use algebraic manipulation or L'Hopital's rule to simplify the expression and then evaluate the limit.

Can the limit of a squareroot combination be negative?

Yes, the limit of a squareroot combination can be negative as long as the function approaches a negative value as the input approaches a given point or value.

What are some common techniques for evaluating limits?

Some common techniques for evaluating limits include using algebraic manipulation, using the properties of limits, applying L'Hopital's rule, and using trigonometric identities.

Are there any special cases when finding the limit of a squareroot combination?

Yes, there are special cases when finding the limit of a squareroot combination, such as when the expression involves indeterminate forms like 0/0 or ∞/∞. In these cases, you may need to use more advanced techniques or evaluate the limit numerically.

Similar threads

Replies
7
Views
2K
Replies
5
Views
2K
Replies
3
Views
1K
Replies
5
Views
2K
Replies
4
Views
650
Replies
2
Views
3K
Replies
6
Views
2K
Back
Top