Integral of infinitely high curve












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I need to find the integral of the curve $frac{1}{x^3}$ bounded by $y = 0, x = 3$. I am unsure of how to take the integral when I have no real lower limit. Is there a way for me to set the lower limit to the limit of $f(x)$ as it approaches 0?










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  • $begingroup$
    Try setting the lower bound of the integral as k, and taking the limit as k approaches 0 of the integral. It turns out this limit does not converge, so the integral doesn't either.
    $endgroup$
    – Neeyanth Kopparapu
    Dec 21 '18 at 23:49






  • 1




    $begingroup$
    There are two possible regions here - either $x<3$ or $x>3$. Which one is intended? You haven't provided enough information to determine.
    $endgroup$
    – jmerry
    Dec 22 '18 at 0:00










  • $begingroup$
    @jmerry he wants $x < 3$ from what I can infer, because otherwise the title wouldn't be named "Integral of infinitely high curve" ;)
    $endgroup$
    – KKZiomek
    Dec 22 '18 at 0:05












  • $begingroup$
    @KKZiomek but he does not say bounded by $x=0$ despite saying bounded by $y=0$
    $endgroup$
    – Henry
    Dec 22 '18 at 0:15










  • $begingroup$
    @Henry I'm reasonably sure it's a typo, and he means $x = 0$ instead of $y = 0$.
    $endgroup$
    – user3482749
    Dec 22 '18 at 0:31
















1












$begingroup$


I need to find the integral of the curve $frac{1}{x^3}$ bounded by $y = 0, x = 3$. I am unsure of how to take the integral when I have no real lower limit. Is there a way for me to set the lower limit to the limit of $f(x)$ as it approaches 0?










share|cite|improve this question











$endgroup$












  • $begingroup$
    Try setting the lower bound of the integral as k, and taking the limit as k approaches 0 of the integral. It turns out this limit does not converge, so the integral doesn't either.
    $endgroup$
    – Neeyanth Kopparapu
    Dec 21 '18 at 23:49






  • 1




    $begingroup$
    There are two possible regions here - either $x<3$ or $x>3$. Which one is intended? You haven't provided enough information to determine.
    $endgroup$
    – jmerry
    Dec 22 '18 at 0:00










  • $begingroup$
    @jmerry he wants $x < 3$ from what I can infer, because otherwise the title wouldn't be named "Integral of infinitely high curve" ;)
    $endgroup$
    – KKZiomek
    Dec 22 '18 at 0:05












  • $begingroup$
    @KKZiomek but he does not say bounded by $x=0$ despite saying bounded by $y=0$
    $endgroup$
    – Henry
    Dec 22 '18 at 0:15










  • $begingroup$
    @Henry I'm reasonably sure it's a typo, and he means $x = 0$ instead of $y = 0$.
    $endgroup$
    – user3482749
    Dec 22 '18 at 0:31














1












1








1





$begingroup$


I need to find the integral of the curve $frac{1}{x^3}$ bounded by $y = 0, x = 3$. I am unsure of how to take the integral when I have no real lower limit. Is there a way for me to set the lower limit to the limit of $f(x)$ as it approaches 0?










share|cite|improve this question











$endgroup$




I need to find the integral of the curve $frac{1}{x^3}$ bounded by $y = 0, x = 3$. I am unsure of how to take the integral when I have no real lower limit. Is there a way for me to set the lower limit to the limit of $f(x)$ as it approaches 0?







calculus integration






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share|cite|improve this question













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edited Dec 21 '18 at 23:58









Foobaz John

22.3k41452




22.3k41452










asked Dec 21 '18 at 23:44









ElijahElijah

626




626












  • $begingroup$
    Try setting the lower bound of the integral as k, and taking the limit as k approaches 0 of the integral. It turns out this limit does not converge, so the integral doesn't either.
    $endgroup$
    – Neeyanth Kopparapu
    Dec 21 '18 at 23:49






  • 1




    $begingroup$
    There are two possible regions here - either $x<3$ or $x>3$. Which one is intended? You haven't provided enough information to determine.
    $endgroup$
    – jmerry
    Dec 22 '18 at 0:00










  • $begingroup$
    @jmerry he wants $x < 3$ from what I can infer, because otherwise the title wouldn't be named "Integral of infinitely high curve" ;)
    $endgroup$
    – KKZiomek
    Dec 22 '18 at 0:05












  • $begingroup$
    @KKZiomek but he does not say bounded by $x=0$ despite saying bounded by $y=0$
    $endgroup$
    – Henry
    Dec 22 '18 at 0:15










  • $begingroup$
    @Henry I'm reasonably sure it's a typo, and he means $x = 0$ instead of $y = 0$.
    $endgroup$
    – user3482749
    Dec 22 '18 at 0:31


















  • $begingroup$
    Try setting the lower bound of the integral as k, and taking the limit as k approaches 0 of the integral. It turns out this limit does not converge, so the integral doesn't either.
    $endgroup$
    – Neeyanth Kopparapu
    Dec 21 '18 at 23:49






  • 1




    $begingroup$
    There are two possible regions here - either $x<3$ or $x>3$. Which one is intended? You haven't provided enough information to determine.
    $endgroup$
    – jmerry
    Dec 22 '18 at 0:00










  • $begingroup$
    @jmerry he wants $x < 3$ from what I can infer, because otherwise the title wouldn't be named "Integral of infinitely high curve" ;)
    $endgroup$
    – KKZiomek
    Dec 22 '18 at 0:05












  • $begingroup$
    @KKZiomek but he does not say bounded by $x=0$ despite saying bounded by $y=0$
    $endgroup$
    – Henry
    Dec 22 '18 at 0:15










  • $begingroup$
    @Henry I'm reasonably sure it's a typo, and he means $x = 0$ instead of $y = 0$.
    $endgroup$
    – user3482749
    Dec 22 '18 at 0:31
















$begingroup$
Try setting the lower bound of the integral as k, and taking the limit as k approaches 0 of the integral. It turns out this limit does not converge, so the integral doesn't either.
$endgroup$
– Neeyanth Kopparapu
Dec 21 '18 at 23:49




$begingroup$
Try setting the lower bound of the integral as k, and taking the limit as k approaches 0 of the integral. It turns out this limit does not converge, so the integral doesn't either.
$endgroup$
– Neeyanth Kopparapu
Dec 21 '18 at 23:49




1




1




$begingroup$
There are two possible regions here - either $x<3$ or $x>3$. Which one is intended? You haven't provided enough information to determine.
$endgroup$
– jmerry
Dec 22 '18 at 0:00




$begingroup$
There are two possible regions here - either $x<3$ or $x>3$. Which one is intended? You haven't provided enough information to determine.
$endgroup$
– jmerry
Dec 22 '18 at 0:00












$begingroup$
@jmerry he wants $x < 3$ from what I can infer, because otherwise the title wouldn't be named "Integral of infinitely high curve" ;)
$endgroup$
– KKZiomek
Dec 22 '18 at 0:05






$begingroup$
@jmerry he wants $x < 3$ from what I can infer, because otherwise the title wouldn't be named "Integral of infinitely high curve" ;)
$endgroup$
– KKZiomek
Dec 22 '18 at 0:05














$begingroup$
@KKZiomek but he does not say bounded by $x=0$ despite saying bounded by $y=0$
$endgroup$
– Henry
Dec 22 '18 at 0:15




$begingroup$
@KKZiomek but he does not say bounded by $x=0$ despite saying bounded by $y=0$
$endgroup$
– Henry
Dec 22 '18 at 0:15












$begingroup$
@Henry I'm reasonably sure it's a typo, and he means $x = 0$ instead of $y = 0$.
$endgroup$
– user3482749
Dec 22 '18 at 0:31




$begingroup$
@Henry I'm reasonably sure it's a typo, and he means $x = 0$ instead of $y = 0$.
$endgroup$
– user3482749
Dec 22 '18 at 0:31










2 Answers
2






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1












$begingroup$

Note that (by definition)
$$
int_{0}^3frac{1}{x^3}, dx=lim_{adownarrow 0}int_{a}^3frac{1}{x^3}=lim_{adownarrow 0}left[-frac{1}{2}x^{-2}right]_{a}^3
$$

which you can compute.






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  • $begingroup$
    If that is the integral the OP meant then it doesn't converge
    $endgroup$
    – DonAntonio
    Dec 22 '18 at 0:48



















1












$begingroup$

Assuming you mean the tiny sliver below the black curve and above and to the right of the red lines in this picture



enter image description here



then you want $$int_{x=3}^infty left(frac1{x^3}-0right) , dx = left[-frac{1}{2x^2}right]^infty_{3} =frac{1}{18}$$






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    2 Answers
    2






    active

    oldest

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    2 Answers
    2






    active

    oldest

    votes









    active

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    active

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    1












    $begingroup$

    Note that (by definition)
    $$
    int_{0}^3frac{1}{x^3}, dx=lim_{adownarrow 0}int_{a}^3frac{1}{x^3}=lim_{adownarrow 0}left[-frac{1}{2}x^{-2}right]_{a}^3
    $$

    which you can compute.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      If that is the integral the OP meant then it doesn't converge
      $endgroup$
      – DonAntonio
      Dec 22 '18 at 0:48
















    1












    $begingroup$

    Note that (by definition)
    $$
    int_{0}^3frac{1}{x^3}, dx=lim_{adownarrow 0}int_{a}^3frac{1}{x^3}=lim_{adownarrow 0}left[-frac{1}{2}x^{-2}right]_{a}^3
    $$

    which you can compute.






    share|cite|improve this answer









    $endgroup$













    • $begingroup$
      If that is the integral the OP meant then it doesn't converge
      $endgroup$
      – DonAntonio
      Dec 22 '18 at 0:48














    1












    1








    1





    $begingroup$

    Note that (by definition)
    $$
    int_{0}^3frac{1}{x^3}, dx=lim_{adownarrow 0}int_{a}^3frac{1}{x^3}=lim_{adownarrow 0}left[-frac{1}{2}x^{-2}right]_{a}^3
    $$

    which you can compute.






    share|cite|improve this answer









    $endgroup$



    Note that (by definition)
    $$
    int_{0}^3frac{1}{x^3}, dx=lim_{adownarrow 0}int_{a}^3frac{1}{x^3}=lim_{adownarrow 0}left[-frac{1}{2}x^{-2}right]_{a}^3
    $$

    which you can compute.







    share|cite|improve this answer












    share|cite|improve this answer



    share|cite|improve this answer










    answered Dec 21 '18 at 23:58









    Foobaz JohnFoobaz John

    22.3k41452




    22.3k41452












    • $begingroup$
      If that is the integral the OP meant then it doesn't converge
      $endgroup$
      – DonAntonio
      Dec 22 '18 at 0:48


















    • $begingroup$
      If that is the integral the OP meant then it doesn't converge
      $endgroup$
      – DonAntonio
      Dec 22 '18 at 0:48
















    $begingroup$
    If that is the integral the OP meant then it doesn't converge
    $endgroup$
    – DonAntonio
    Dec 22 '18 at 0:48




    $begingroup$
    If that is the integral the OP meant then it doesn't converge
    $endgroup$
    – DonAntonio
    Dec 22 '18 at 0:48











    1












    $begingroup$

    Assuming you mean the tiny sliver below the black curve and above and to the right of the red lines in this picture



    enter image description here



    then you want $$int_{x=3}^infty left(frac1{x^3}-0right) , dx = left[-frac{1}{2x^2}right]^infty_{3} =frac{1}{18}$$






    share|cite|improve this answer











    $endgroup$


















      1












      $begingroup$

      Assuming you mean the tiny sliver below the black curve and above and to the right of the red lines in this picture



      enter image description here



      then you want $$int_{x=3}^infty left(frac1{x^3}-0right) , dx = left[-frac{1}{2x^2}right]^infty_{3} =frac{1}{18}$$






      share|cite|improve this answer











      $endgroup$
















        1












        1








        1





        $begingroup$

        Assuming you mean the tiny sliver below the black curve and above and to the right of the red lines in this picture



        enter image description here



        then you want $$int_{x=3}^infty left(frac1{x^3}-0right) , dx = left[-frac{1}{2x^2}right]^infty_{3} =frac{1}{18}$$






        share|cite|improve this answer











        $endgroup$



        Assuming you mean the tiny sliver below the black curve and above and to the right of the red lines in this picture



        enter image description here



        then you want $$int_{x=3}^infty left(frac1{x^3}-0right) , dx = left[-frac{1}{2x^2}right]^infty_{3} =frac{1}{18}$$







        share|cite|improve this answer














        share|cite|improve this answer



        share|cite|improve this answer








        edited Dec 22 '18 at 10:42

























        answered Dec 22 '18 at 0:13









        HenryHenry

        100k481168




        100k481168






























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