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Thread: Help in partial differential equations

  1. #1
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    Help in partial differential equations

    مرحبا بالجميع
    أنا أطلب منك أن تساعدني في حل السؤال التالي:


    س: العثور على سلسلة فورييه وظيفة فترة و ( س ) = ه - | س | ، - 1 س 1.


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  2. #2
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    Re: Help in partial differential equations

    It might be real hard to get help if is post in a language other than English.
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  3. #3
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    Re: Help in partial differential equations

    Google suggests:
    Hello Paljmaaona ask you to help me in solving the following question: Q: Finding a Fourier series and the function f (x) = e - | x |, - 1 ≤ x ≤ 1.
    Now, I suppose that the function is suppose to be $f(x) = \mathrm e^{|x|}$ in the interval $[-1, 1]$.

    The first thing to notice is that this is an even function. Therefore it's Fourier Series will be a Cosine series $${a_0 \over 2} + \sum_{n=1}^\infty a_n\cos {(\pi n x)}$$
    where the $a_n$ are given by$$\int_{-1}^1 \mathrm e^{|x|}\cos {(\pi n x)} \, \mathrm d x$$
    But because these are even functions we know that$$\int_{-1}^1 \mathrm e^{|x|}\cos {(\pi n x)} \, \mathrm d x = 2\int_0^1 \mathrm e^{x}\cos {(\pi n x)} \, \mathrm d x$$
    Can you proceed from here?
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  4. #4
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    Re: Help in partial differential equations

    Excuse me dear

    Pay attention to the language

    This is the question again:


    Find the Fourier series of the period function f(x) = e−| x|, −1 ≤ x ≤ 1.
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  5. #5
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    Re: Help in partial differential equations

    Quote Originally Posted by saif73 View Post
    مرحبا بالجميع
    أنا أطلب منك أن تساعدني في حل السؤال التالي:


    س: العثور على سلسلة فورييه وظيفة فترة و ( س ) = ه - | س | ، - 1 س 1.




    ...Ok people, here's a side challenge. Without any prior knowledge of Arabic, prove that it is written from right to left.
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  6. #6
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    Re: Help in partial differential equations

    Quote Originally Posted by Rebesques View Post
    ...Ok people, here's a side challenge. Without any prior knowledge of Arabic, prove that it is written from right to left.
    Direction of inequalities?
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