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Math Help - Finding function (integration)

  1. #1
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    Finding function (integration)

    Find a function f such that f(1) = 0 and f'(x) = 2^(x) / x
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    Quote Originally Posted by TsAmE View Post
    Find a function f such that f(1) = 0 and f'(x) = 2^(x) / x
    f(x) = \int_1^x \frac{2^t}{t} \, dt.
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    Quote Originally Posted by mr fantastic View Post
    f(x) = \int_1^x \frac{2^t}{t} \, dt.
    I love it when it's simple ...
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    Arent you suppose to find the anti-derivative of f'(x) = 2^(x) / x?
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    Quote Originally Posted by TsAmE View Post
    Arent you suppose to find the anti-derivative of f'(x) = 2^(x) / x?
    In that case, good luck ....
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    Quote Originally Posted by mr fantastic View Post
    In that case, good luck ....
    I am not sure of the method you used, thats why I asked, as I thought that the only of finding it was by using an anti-derivative
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  7. #7
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    Mr F did not use any method ..

    He get the answer by using the FTC ..

    The problem here is that \int \frac{2^x}{x} \, dx is unelementary integral ..

    What ever you do, you can not evaluate it in terms of elementary functions ..
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