Strange question about exponentsBasic math questionQuestion about the graph of the square root functionHint...

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Strange question about exponents


Basic math questionQuestion about the graph of the square root functionHint to show $tanh(z)=frac{sinh(2x)+isin(2y)}{cosh(2x)+cos(2y)}$?Algebra Fraction Problem - VariableA bowler has averaged 164 for the first 21 games of a 90-game season.Find $limlimits_{xto 0} frac{sqrt{ 1+x} - sqrt{ 1-x}}{sqrt[3]{ 1+x} - sqrt[3]{ 1-x}}$Question about Properties of ExponentsEvaluating $lim _{tto infty}frac{1-frac{sqrt{t}}{sqrt{t+1}}}{2-frac{sqrt{4t:+:1}}{sqrt{t+2}}}$Help with function question $f(2x + 1) = 2f(x) + 1$How to solve this simple Algebraic equation? (Wolfram & SymboLab both stumped…)













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I've been stumped for a while trying to figure out the flaw in this logic. Consider some positive, real x. Then



$$e^{ix} = e^{2pi ifrac{x}{2pi}} = (e^{2pi i})^{frac{x}{2pi}} = 1^{frac{x}{2pi}} = 1$$



I've felt like an idiot for hours. What am I missing?










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$endgroup$












  • $begingroup$
    Perhaps an analogy would be something like $(-1)^x = (-1)^{2frac{x}{2}} = left[(-1)^2right]^{frac{x}{2}} = 1^{frac{x}{2}} = 1.$ I've simply written essentially the same string of equalities you've written using $e^{pi i}$ in place of $e^{i}.$
    $endgroup$
    – Dave L. Renfro
    Mar 13 at 9:06
















1












$begingroup$


I've been stumped for a while trying to figure out the flaw in this logic. Consider some positive, real x. Then



$$e^{ix} = e^{2pi ifrac{x}{2pi}} = (e^{2pi i})^{frac{x}{2pi}} = 1^{frac{x}{2pi}} = 1$$



I've felt like an idiot for hours. What am I missing?










share|cite|improve this question









$endgroup$












  • $begingroup$
    Perhaps an analogy would be something like $(-1)^x = (-1)^{2frac{x}{2}} = left[(-1)^2right]^{frac{x}{2}} = 1^{frac{x}{2}} = 1.$ I've simply written essentially the same string of equalities you've written using $e^{pi i}$ in place of $e^{i}.$
    $endgroup$
    – Dave L. Renfro
    Mar 13 at 9:06














1












1








1





$begingroup$


I've been stumped for a while trying to figure out the flaw in this logic. Consider some positive, real x. Then



$$e^{ix} = e^{2pi ifrac{x}{2pi}} = (e^{2pi i})^{frac{x}{2pi}} = 1^{frac{x}{2pi}} = 1$$



I've felt like an idiot for hours. What am I missing?










share|cite|improve this question









$endgroup$




I've been stumped for a while trying to figure out the flaw in this logic. Consider some positive, real x. Then



$$e^{ix} = e^{2pi ifrac{x}{2pi}} = (e^{2pi i})^{frac{x}{2pi}} = 1^{frac{x}{2pi}} = 1$$



I've felt like an idiot for hours. What am I missing?







algebra-precalculus






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asked Mar 13 at 7:46









louie mcconnelllouie mcconnell

1,4881824




1,4881824












  • $begingroup$
    Perhaps an analogy would be something like $(-1)^x = (-1)^{2frac{x}{2}} = left[(-1)^2right]^{frac{x}{2}} = 1^{frac{x}{2}} = 1.$ I've simply written essentially the same string of equalities you've written using $e^{pi i}$ in place of $e^{i}.$
    $endgroup$
    – Dave L. Renfro
    Mar 13 at 9:06


















  • $begingroup$
    Perhaps an analogy would be something like $(-1)^x = (-1)^{2frac{x}{2}} = left[(-1)^2right]^{frac{x}{2}} = 1^{frac{x}{2}} = 1.$ I've simply written essentially the same string of equalities you've written using $e^{pi i}$ in place of $e^{i}.$
    $endgroup$
    – Dave L. Renfro
    Mar 13 at 9:06
















$begingroup$
Perhaps an analogy would be something like $(-1)^x = (-1)^{2frac{x}{2}} = left[(-1)^2right]^{frac{x}{2}} = 1^{frac{x}{2}} = 1.$ I've simply written essentially the same string of equalities you've written using $e^{pi i}$ in place of $e^{i}.$
$endgroup$
– Dave L. Renfro
Mar 13 at 9:06




$begingroup$
Perhaps an analogy would be something like $(-1)^x = (-1)^{2frac{x}{2}} = left[(-1)^2right]^{frac{x}{2}} = 1^{frac{x}{2}} = 1.$ I've simply written essentially the same string of equalities you've written using $e^{pi i}$ in place of $e^{i}.$
$endgroup$
– Dave L. Renfro
Mar 13 at 9:06










1 Answer
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$begingroup$

$z to z^{frac x {2pi}}$ is a mutivalued function and just one of its values for $z=e^{2pi i}$ is $e^{2pi ifrac x {2pi}}$. So you cannot conclude that $e^{ix}=1$.



To understand exactly what is happening you have to get familiar with logarithms in the complex plane.






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    $begingroup$

    $z to z^{frac x {2pi}}$ is a mutivalued function and just one of its values for $z=e^{2pi i}$ is $e^{2pi ifrac x {2pi}}$. So you cannot conclude that $e^{ix}=1$.



    To understand exactly what is happening you have to get familiar with logarithms in the complex plane.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      $z to z^{frac x {2pi}}$ is a mutivalued function and just one of its values for $z=e^{2pi i}$ is $e^{2pi ifrac x {2pi}}$. So you cannot conclude that $e^{ix}=1$.



      To understand exactly what is happening you have to get familiar with logarithms in the complex plane.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        $z to z^{frac x {2pi}}$ is a mutivalued function and just one of its values for $z=e^{2pi i}$ is $e^{2pi ifrac x {2pi}}$. So you cannot conclude that $e^{ix}=1$.



        To understand exactly what is happening you have to get familiar with logarithms in the complex plane.






        share|cite|improve this answer









        $endgroup$



        $z to z^{frac x {2pi}}$ is a mutivalued function and just one of its values for $z=e^{2pi i}$ is $e^{2pi ifrac x {2pi}}$. So you cannot conclude that $e^{ix}=1$.



        To understand exactly what is happening you have to get familiar with logarithms in the complex plane.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Mar 13 at 7:51









        Kavi Rama MurthyKavi Rama Murthy

        68.9k53169




        68.9k53169






























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