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Homework Help: Cosh2x+2sinh^2x, not sure if this goes in this forum

  1. May 8, 2010 #1
    1. The problem statement, all variables and given/known data

    Express the function cosh(2x)+2 sinh^2(x)= in terms of exponential functions.

    2. Relevant equations



    3. The attempt at a solution
    i have an answer but im not sure if its right can someone check please.
    =1/2 (e^2x+e^(-2x) )+1/2(e^2x-e^(-2x)) if this is right i need some help simplifying.
     
  2. jcsd
  3. May 8, 2010 #2

    vela

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    No, it's not right. Check your algebra.
     
  4. May 9, 2010 #3
    almost certain that the problem is the 2sinh^2(x), i got 1/2(e^x-e^(-x))^2 which my 89 says is right, then i try to simplify to 1/2(e^(2x)-e^-(2x)) which it says is wrong but i cant see why??????????
     
  5. May 9, 2010 #4

    vela

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    If you're trying to say (a+b)2 = a2+b2, that's the reason why. It's not true. You need to FOIL it out. Also, the 1/2 shouldn't be there because it cancels with the 2 in front.
     
  6. May 9, 2010 #5
    thanks i agree with one problem you found but i think that the 1/2 should still be there because its squared in sinh^2 (the 2 isnt) giving 1/4 which then becomes 1/2???????????????? not positive though??
     
  7. May 9, 2010 #6

    vela

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    Oops, you're right. Sorry.
     
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