How to solve this limit? (difference of two square rooted terms)

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SUMMARY

The limit problem presented involves evaluating the expression \(\lim_{x\to +\infty}(\sqrt{x^2+ax+b}-\sqrt{x^2-ax+b})\). The solution technique involves multiplying the expression by \(\frac{\sqrt{x^2+ax+b} + \sqrt{x^2-ax+b}}{\sqrt{x^2+ax+b} + \sqrt{x^2-ax+b}}\), which simplifies the limit to \(a\). This approach effectively resolves the limit by eliminating the indeterminate form.

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mnb96
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Hello,
do you have a hint on how to solve this limit?

[tex]\lim_{x\to +\infty}(\sqrt{x^2+ax+b}-\sqrt{x^2-ax+b})[/tex]

Thanks!
 
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When I see an expression of the form

[tex]\sqrt{A} - \sqrt{B}[/tex]

I think of multiplying it by

[tex]\frac{\sqrt{A} + \sqrt{B}}{\sqrt{A} + \sqrt{B}}[/tex]

Does that help?

Petek
 
Thanks a lot!
that trick made the job. The limit of that expression is a
 

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