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Homework Help: Solving the limit of a function with no calculator

  1. Sep 19, 2011 #1
    The Limx-->infinity of the function Square rt(5x^4+2x) / (x^2)

    Note* The square root is only in the numerator for the expression (5x^4+2x)

    I have tried multiplying by the complex conjugate but I am not sure if this is the correct way to do it.

    I did sqrt(5x^4-2x) over itself and got sqrt 25x^8-4x / x^2

    I had that as my answer, but my teacher told me this was incorrect. If anyone could help and explain that would be great! Thanks a lot!
  2. jcsd
  3. Sep 19, 2011 #2


    Staff: Mentor

    Factor x4 out of both terms inside the radical, and bring this out as x2. You should be able to evaluate the limit then.
  4. Sep 19, 2011 #3
    I'm not clear on what you mean by that. I understand factoring out the x^4 from the 5x^4 but not the 2x.
  5. Sep 19, 2011 #4
    If you factor out x^4 from 2x, you are left with 2/x^3.
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