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So I'm having trouble with the following limit:


Common factor doesn't work. Any hints on how to tackle it?

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L'Hôpital's rule – user22805 Sep 20 '12 at 4:47
Do you know how to differentiate the denominator? If so, you can apply L'hopital's Rule. – Owen Biesel Sep 20 '12 at 4:48
up vote 8 down vote accepted


  1. How about multiplying numerator and denominator by $\sqrt{x^2+5} +3$
  2. Can you then factor numerator and denominator and see any factors that cancel?
  3. You should be able to take it from there.

Make sense?


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Thanks! I did an identical exercise this morning, I can't believe how I missed the conjugate!. – Julián Sep 20 '12 at 4:54
Excellent! I would also suggest trying it using the definition of limits and see if you can work through it. – Amzoti Sep 20 '12 at 4:55

Hint: Try using L'Hopital's rule

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I don't know it yet – Julián Sep 20 '12 at 4:50
Ahh then Amzoti's answer is the way to go :) – noahklein Sep 20 '12 at 4:56

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