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Homework Help: Simple but cant solve it

  1. May 20, 2010 #1
    Can someone show me in steps how to manipulate this formula in attachement to obtain 1/(sqr(w^2+4)? Thanks
     

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  2. jcsd
  3. May 20, 2010 #2

    jack action

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    The two equations are not equal. Just replace w by any value and you'll see that both equations give different answers.
     
  4. May 20, 2010 #3

    Mentallic

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    The best you can really get is:

    [tex]\frac{\sqrt{4-w^2}}{w^2+4}[/tex]
     
    Last edited: May 20, 2010
  5. May 20, 2010 #4

    Mentallic

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    You must have made a typo. The expression should be,

    [tex]\sqrt{\left(\frac{2}{w^2+4}\right)^2+\left(\frac{w}{w^2+4}\right)^2}[/tex]
     
  6. May 20, 2010 #5
    Hmm, thats quite possible. Then how to get that solution?
     
  7. May 20, 2010 #6

    Mentallic

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    Well I can't just give you the answer, you need to show an attempt at solving the problem first.

    But I can give you some hints, you can most certainly find the answer by using a combination of these rules:

    [tex]\sqrt{\frac{a}{b}}=\frac{\sqrt{a}}{\sqrt{b}}[/tex]

    [tex]\sqrt{a^2b}=|a|\sqrt{b}[/tex] (the |a| means the positive of a, but remember that for any real number n, n2 is always positive).

    [tex]\frac{a}{c}+\frac{b}{c}=\frac{a+b}{c}[/tex]

    [tex]\frac{\sqrt{a}}{a}=\frac{1}{\sqrt{a}}[/tex]


    Good luck! :smile:
     
  8. May 21, 2010 #7
    Hello, I am sorry but it just does not work. What am I doing work? Thanks
     

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  9. May 21, 2010 #8

    Cyosis

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    You're adding fractions, but you're multiplying numerators.
     
  10. May 21, 2010 #9
    AAA, stupid me:) Thanks
     
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