Finding the value of integral.












2












$begingroup$


If $ int_{-infty}^{infty} f(x) dx= 1,$
Find value of $ int_{-infty}^{infty} f(x-frac{1}{x}) dx$.



I tried substituting $x$ as $frac{1}{t}$, but nothing is happening.
In the denominator, $1+x^2$ is left.










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$endgroup$












  • $begingroup$
    Hint: Try substituting $x=e^u$.
    $endgroup$
    – John Doe
    Jan 5 at 17:49










  • $begingroup$
    @JohnDoe Your substitution only works for $xin(0,infty)$.
    $endgroup$
    – Matemáticos Chibchas
    Jan 13 at 6:01










  • $begingroup$
    @matematicoschibchas hmm, you're right. You can split it the integral range into positive and negative $x$, then use $x=-e^{-u}$ for the negative part.
    $endgroup$
    – John Doe
    Jan 14 at 2:20


















2












$begingroup$


If $ int_{-infty}^{infty} f(x) dx= 1,$
Find value of $ int_{-infty}^{infty} f(x-frac{1}{x}) dx$.



I tried substituting $x$ as $frac{1}{t}$, but nothing is happening.
In the denominator, $1+x^2$ is left.










share|cite|improve this question











$endgroup$












  • $begingroup$
    Hint: Try substituting $x=e^u$.
    $endgroup$
    – John Doe
    Jan 5 at 17:49










  • $begingroup$
    @JohnDoe Your substitution only works for $xin(0,infty)$.
    $endgroup$
    – Matemáticos Chibchas
    Jan 13 at 6:01










  • $begingroup$
    @matematicoschibchas hmm, you're right. You can split it the integral range into positive and negative $x$, then use $x=-e^{-u}$ for the negative part.
    $endgroup$
    – John Doe
    Jan 14 at 2:20
















2












2








2





$begingroup$


If $ int_{-infty}^{infty} f(x) dx= 1,$
Find value of $ int_{-infty}^{infty} f(x-frac{1}{x}) dx$.



I tried substituting $x$ as $frac{1}{t}$, but nothing is happening.
In the denominator, $1+x^2$ is left.










share|cite|improve this question











$endgroup$




If $ int_{-infty}^{infty} f(x) dx= 1,$
Find value of $ int_{-infty}^{infty} f(x-frac{1}{x}) dx$.



I tried substituting $x$ as $frac{1}{t}$, but nothing is happening.
In the denominator, $1+x^2$ is left.







definite-integrals






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share|cite|improve this question













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edited Jan 5 at 17:38









Gnumbertester

558112




558112










asked Jan 5 at 17:22









Math_centricMath_centric

161




161












  • $begingroup$
    Hint: Try substituting $x=e^u$.
    $endgroup$
    – John Doe
    Jan 5 at 17:49










  • $begingroup$
    @JohnDoe Your substitution only works for $xin(0,infty)$.
    $endgroup$
    – Matemáticos Chibchas
    Jan 13 at 6:01










  • $begingroup$
    @matematicoschibchas hmm, you're right. You can split it the integral range into positive and negative $x$, then use $x=-e^{-u}$ for the negative part.
    $endgroup$
    – John Doe
    Jan 14 at 2:20




















  • $begingroup$
    Hint: Try substituting $x=e^u$.
    $endgroup$
    – John Doe
    Jan 5 at 17:49










  • $begingroup$
    @JohnDoe Your substitution only works for $xin(0,infty)$.
    $endgroup$
    – Matemáticos Chibchas
    Jan 13 at 6:01










  • $begingroup$
    @matematicoschibchas hmm, you're right. You can split it the integral range into positive and negative $x$, then use $x=-e^{-u}$ for the negative part.
    $endgroup$
    – John Doe
    Jan 14 at 2:20


















$begingroup$
Hint: Try substituting $x=e^u$.
$endgroup$
– John Doe
Jan 5 at 17:49




$begingroup$
Hint: Try substituting $x=e^u$.
$endgroup$
– John Doe
Jan 5 at 17:49












$begingroup$
@JohnDoe Your substitution only works for $xin(0,infty)$.
$endgroup$
– Matemáticos Chibchas
Jan 13 at 6:01




$begingroup$
@JohnDoe Your substitution only works for $xin(0,infty)$.
$endgroup$
– Matemáticos Chibchas
Jan 13 at 6:01












$begingroup$
@matematicoschibchas hmm, you're right. You can split it the integral range into positive and negative $x$, then use $x=-e^{-u}$ for the negative part.
$endgroup$
– John Doe
Jan 14 at 2:20






$begingroup$
@matematicoschibchas hmm, you're right. You can split it the integral range into positive and negative $x$, then use $x=-e^{-u}$ for the negative part.
$endgroup$
– John Doe
Jan 14 at 2:20












1 Answer
1






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$begingroup$

One may recall the following property
$$
int_{-infty}^{+infty} f(x) , dx = int_{-infty}^{+infty} fleft( x - frac{1}{x} right) , dx
$$
proved here.






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    1 Answer
    1






    active

    oldest

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3












    $begingroup$

    One may recall the following property
    $$
    int_{-infty}^{+infty} f(x) , dx = int_{-infty}^{+infty} fleft( x - frac{1}{x} right) , dx
    $$
    proved here.






    share|cite|improve this answer









    $endgroup$


















      3












      $begingroup$

      One may recall the following property
      $$
      int_{-infty}^{+infty} f(x) , dx = int_{-infty}^{+infty} fleft( x - frac{1}{x} right) , dx
      $$
      proved here.






      share|cite|improve this answer









      $endgroup$
















        3












        3








        3





        $begingroup$

        One may recall the following property
        $$
        int_{-infty}^{+infty} f(x) , dx = int_{-infty}^{+infty} fleft( x - frac{1}{x} right) , dx
        $$
        proved here.






        share|cite|improve this answer









        $endgroup$



        One may recall the following property
        $$
        int_{-infty}^{+infty} f(x) , dx = int_{-infty}^{+infty} fleft( x - frac{1}{x} right) , dx
        $$
        proved here.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Jan 5 at 17:30









        Olivier OloaOlivier Oloa

        108k17177294




        108k17177294






























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