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Homework Help: Basic Limit Question

  1. Sep 3, 2011 #1
    I'm stuck on this one problem:
    lim (x=>0) cos^2x-1/x^2

    I know the answer is -1, however I'm having trouble getting there.

    Can anyone help me with this? I know cos^2x-1 is also -sin^2x and I'm having trouble with getting rid of the denominator. Thanks!
  2. jcsd
  3. Sep 3, 2011 #2
    So you know the following limit??

    [tex]\lim_{x\rightarrow 0}{\frac{\sin(x)}{x}}[/tex]


    If you don't know it, then you can calculate it with L'Hopitals rule. This limit will help you with the limit in the OP...
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